The "seldom seen" RPO thread
 

Thought it might be nice to share options we've stumbled across on SPIDs over the years that we don't see every day - that haven't already had several other dedicated threads written about them (like A50 bucket seats - although rare and very desirable, there are already some great threads on here about them). I'm talkin about RPOs that make you scratch your head, stuff you've only seen a few times - so, "rare" yes, but doesn't matter if they are desirable or not. I'll go first to get the ball rolling:

You all know I love RPOs :) but this one has made me dig, and I haven't hit paydirt yet: ZQ5 - Std Truck Trim.

(btw, I think this is a pretty cool truck - white/saddle Custom Camper Longhorn with LS8, K28, and U15 - nice... and I'd submit that K28 and U15 are also "seldom seen" RPOs).

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Like your example above my 69 CST20 has the LS8 HD 350 V8 option on the SPID. I’ve never seen another truck with that engine option but my own. Your Longhorn example is the second. LS9 is the typical 350 in our trucks. I was really bummed when I pulled the engine out of my truck and found it’s a service replacement. I was hoping during teardown I could find a specific differences between the LS9and the LS8. I tried digging around but I have never found any solid information on the differences between the two engines.

Steve weim55 Colorado

Re: The "seldom seen" RPO thread
 

Steve, I believe the LS8 was more of a medium duty engine, but available in light duty trucks. I believe Pic 1 is an LS9, though the RPOs aren't labeled in the engine descriptions. And I believe Pic 2 is the LS8 - note it had a 2 bbl and lower compression. But, I agree, there's not much info available on the differences. As for LS8s in light duty trucks, I can only recall seeing them in C20/30s, but they were available in 10s (and Ks). Last pic (the little skinny excerpt from the optional equipment list in 69 that probably looks like it's attached to the bottom of the first pic, depending on how wide your screen is..), shows the very slight difference in wording between LS9 and LS8 RPOs - i.e. the LS8 being "heavy duty". I am curious what made it heavier duty than the LS9 though. Some have surmised 4-bolt mains, others nodular crank, but that could be had in LS9 if I'm not mistaken. Hmm. Thanks for sharing. Btw - does your 69 CST 20 with the LS8 also happen to have the optional K28 fuel filter?

Re: The "seldom seen" RPO thread
 

I just learned something about the truck I've owned all these years. My original 350 is also a LS8.

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Well, I can either shed a little light on some of this or make it thoroughly confusing.....
First off, K28 is actually fairly common on GMC's with the V-6 (my truck has one). Maybe it's because of the heavy duty nature of the V-6, or the very small standard fuel filter in the Stromberg carburetor. Or the V-6's tremendous appitite for gasoline! As for standard duty and heavy duty 350's, this is interesting: The 'High Torque' 350 2 bbl. in the upper picture is the version for series 40 and larger trucks, not pickups. No AIR pump, commercial type air cleaner. But, there are actually many versions of the 350 specifically for pickups. I have a '67-'69 GMC parts book, and it breaks them down by the 2 letter code stamped on the block. All the codes starting with 'W' are listed as light duty, all starting with 'X' are listed as medium duty. The list is long, 17 different versions of the 350 4 bbl. and these are all for the 10/20/30 series trucks. There is also a lot of overlap, for instance 'WK' and 'XD' are both 350 4 bbl. with Hydramatics, 'WK' listed as light duty, 'XD' listed as medium duty. All 350's listed are 4 bbl. and regular gas for series 10/20/30. I don't believe the 350 2bbl. engine pictured is an LS8, because the second picture clearly states the 'heavy duty' CE/KE 10 350 did come with a 4bbl.. I think the engine referenced in the second picture would be an 'XA' or 'XW' code with an AIR pump, or an 'XB' or 'XS' without. Unfortunately, the parts book doesn't seem to break the engine down by R.P.O. like they do now. The 350 is the only engine that has both light and medium duty versions, but I believe that is because all 250's and 307's are considered light duty, and all 292's are considered medium duty. To further confuse matters this engine list does not show any 2bbl. 350's, but I am pretty sure they did exist in 1969, and the parts text shows a Rochester 2bbl. for the '69 350. Then there is that 1968 396 with the Holley 2bbl.. Carb. # R4147A if anyone asks. Does anyone have a copy of the 1969 Chevy Truck Data Book? That would straighten a lot of this out.

Re: The "seldom seen" RPO thread
 

Digging a little deeper I found in the parts text there are some differences between 'light duty' and 'medium duty' 350's. Unfortunately, it doesn't specifically say what the differences are, it just shows different part numbers. For instance, the light duty crank is a 3932444, medium duty is a 3941180. One is probably forged, the other is cast. The medium duty 350 has valve rotators, light duty does not. Blocks are different, medium duty is part #3961475, which could be a 4 bolt main. So, there is a difference.

Re: The "seldom seen" RPO thread
 

Jim, like your truck the build sheet from my August 68 production date 1969 CST20 shows an “XD” code LS8 medium duty 350 as original equipment. One of the deciding factors in my purchase of the truck was the absolute virgin bone original engine compartment. Every last bracket an accessory on the engine is as it should’ve been in 1969. I thought for sure this would be the original engine in the truck, but alas, when I removed it to reseal it I found it is actually a std. “WH” code LS9 350 with casting dates in the spring/summer 1969. Every single component of the engine was untouched and correct so possibly this was a warranty replacement Engine? When I opened up the engine all of the original gaskets were Still in place, the old fiber timing gear still on it, all of the original bearings and pistons. Definitely never opened from all the evidence. As you can see in the pictures this LS nine has a different block casting from yours. The very common “010” 350 Passenger car/light truck use from the late 60s into the mid 70s. This one happens to have four Bolt mains as you can see in the pictures. Other things I noted : Cast crankshaft, not forged. Cylinder heads do not have valve rotators. Cylinder heads are small valve small port (1.74-1.50) Castings that are also the same on 307 engines of the same year. Intake manifold is a small port that matches the heads topped with the correct Quadra jet four barrel. I think it is highly likely the difference in the LS8 block casting is a higher nickel content for reduced cylinder bore wear And possibly thicker cylinder walls. I am curious as to the other small differences.

Steve weim55 Colorado

Re: The "seldom seen" RPO thread
 

does your 69 CST 20 with the LS8 also happen to have the optional K28 fuel filter?[/QUOTE]


My LS8 truck does not have the optional K 28 fuel filter listed on the SPID. My truck is very original and shows no evidence of any other fuel filter other than the small filter in the carburetor.

Steve weim55 Colorado

Re: The "seldom seen" RPO thread
 

My LS8 truck does not have the optional K 28 fuel filter listed on the SPID. My truck is very original and shows no evidence of any other fuel filter other than the small filter in the carburetor.

Steve weim55 Colorado[/QUOTE]

It does not and never did.

Re: The "seldom seen" RPO thread
 

Thanks Jim, Steve - was just curious if it was commonly paired w/LS8, but clearly not the case. Great to have folks with original trucks with SPIDs on the board!

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Factory grill guard listed on the spid

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Wow, I honestly would have never guessed that was a SPID option. Interesting, I would think it would be more common, lots of people buying trucks in that era probably would want one.

My own "white whale" is not particularly interesting, but a lack of info on it has made me fascinated with the J76 Park Brake Prop Shaft on my 68 C20. Its an option that should not exist on light duty trucks. I have found mention of a few existing by members of this site... although absolutely no pictures seem to be on the forum of this option on a 67-72. I am therefore trying to put it together without knowing precisely how it should look or function, I will post some pics this weekend hopefully.

The fact that all trucks that I have found that have the J76 option were made at the Oshawa plant makes me wonder if only certain plants were equipped to fulfill certain orders. I would think it makes sense, anyone know for sure?

Re: The "seldom seen" RPO thread
 

D29 is an interesting one too, Canada only maybe?

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D29 refers to the painted version of the 7.5" x 10.5" below eyeline mirrors (after 1968) and west coast junior 6" x 11" mirrors on 67s and 68s which are fairly common. Perhaps Oshawa used a different description.

Re: The "seldom seen" RPO thread
 

As far as I can tell, the D29 option was for a style of mirror that appears to be West Coast Junior, but for one reason or another was cited as being slightly different from those mirrors that actually were called WCJ's. WCJ's of course have their own SPID code.

Perhaps the difference was simply that D29's were not chromed or not as fancy in their design, I don't know. The mirrors that I had on the truck were definitely original, though.

The Z49 code is as Canadian as it comes, and is on all Oshawa trucks. No idea what it includes, I would say maybe block heaters, but they have their own SPID code as well.

EDIT FirstOwner69 was posting at the same time as me, and said it better. Interesting that there were so many mirror options, even those of the same style and function.

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It's also interesting that the DG4 mirrors (chrome version of the '69 D29s) are listed on my '69 SPID (post #4 above) as as "W/C Mirror-JR LH&RH", but were eventually referred to as Below Eyeline mirrors.

Confused now?

Re: The "seldom seen" RPO thread
 

Here is a list of RPO codes from "T" to "Z"
Z49 says: EXPORT CANADIAN MODIFICATION MANDATORY BASE EQUIPMENT but does not go into detail as to what that includes.

http://www.rpocodes.com/GM-RPO-codes...TthroughZ.html

Re: The "seldom seen" RPO thread
 

Still no ZQ5 though! (Post #1)... Many of the RPOs on that website appear to be rather generic or for T800 and newer - have never seen YE9 referred to as "CONVENIENCE PACKAGE, COMFORT & DECOR LEVEL #3" - though it did evolve from Cheyenne Super to Silverado in the early square years.

Re: The "seldom seen" RPO thread
 

I saved this spid from the forum at one point since it was interesting. I don't know if these were typical for canadian trucks or not, but I've never seen the sunshade or beige interior...

Attachment 2023072

Re: The "seldom seen" RPO thread
 

The sundshade is a right side sun visor which I believe was an option on base level '67s. It's more likely you've never seen a truck without one.

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That’s odd

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How about R05 dual rear wheels on a '67-'68 GMC 2500? Was an option on cowl, chassis-cab or platform (stake bed). There actually was a specific reason for that option on a 3/4 ton. In those years, the 2500's were all on the 127" wheel base which is for an 8' bed. Shortest 3500 was on a 133" wheelbase, which is for a 9' bed (and the reason all 3500 pickups were 9' Fender-Sides). So, the customer needing a high GVW truck for a 8' bed had a truck to buy. GMC offered a factory 8' platform/stake bed truck (2590F models) in single or dual rear wheels, but I suspect that most of the 2500 R05 trucks were cowls (2590M models) used for milk delivery trucks.

Did Chevy offer R05 on the C-20? I wonder if there is such a thing as a dual rear wheel Eaton rear axle set up for coil springs. I know I have never seen anything like that.

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1/2 ton with Factory clearance lights?

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No paint codes. Not even on the build sheet either. Just notice it's an LS9

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The 4x4 front axle posi option I’m sure qualifies for this thread, I’ve only seen it pop up on here a few times. Here’s a blazer example from a while back.