Yet to be named... ‘78 K10 Suburban

[RyanAK]

After 6 months of searching... within days of selling Earl... I found my new truck in Montana. It arrived last week and I’ve managed to get a few things done. Nice, solid survivor with a new GM crate 350. Clean and stock, but still so much to do. I’ll update when I can, but here’s an ‘as arrived’ and ‘as of now’...

Morning after I got it off the trailer...


And a week in. I did a lot of small things beyond removing the running boards and big, honkin’ towing flaps, but it’s all pretty banal stuff.



Need to get tires sorted (15x6 wheels... ugh...) and figure out a deep hum-rumble-vibration that shows up between 45-50mph. Hopefully u-joints or an unbalanced tire and not something more drastic. Then a hub swap, then... then... then...

More soon!

[Katrina/10]

Beautiful truck, looks even better without the running boards and mud flaps.

[RyanAK]

Thanks, Gary. I think the family and I are gonna enjoy it. Some things to go through, but that’s always the case, yeah?

R

[TKCR]

Wow, that looks very nice. Can you post some interior pics?

[RyanAK]

Thanks! Interior is pretty nice. Bone stock and clean. I haven’t been able to take any interior photos yet, but here are a few from the seller. Piping on driver’s seat needs replaced. Hard headliner drooping slightly in the front. Otherwise, I like it!

[TKCR]

Wow that looks very nice! Wish I could find a nice Burb like that.

[ShortHaul]

What a beauty!!

[RyanAK]

Took about 6 months of serious searching coast-to-coast. This truck checks almost all the boxes. Some rust scabs that I need to get a plan for... needs u-joints... and the NP203 full-time 4WD is a mystery at this point. But I think this is a good starting point for an everyday truck and family adventure rig. Only minor disappointment is just how limited tire choice is for stock 15x6 steel wheels. My preference is to run the dog dish caps, but I’d really like a taller tire for driving the forest roads and to get the highway RPMs a bit lower. These Toyos don’t have much life left, so wheels/tires are a near term consideration.

Tough to tell in the photos since the paint is pretty oxidized, but this is a code 71 metallic red and tan truck. Here’s a ‘78 GM promotional shot of a Suburban in these colors. Pretty inspirational!

[Katrina/10]

I think the rally wheels look great in the photo and would look great on your truck. Put some 31x10.50 tires on them for a little off road use, and you're all set.

[RyanAK]

15x8 rally wheels are certainly an option. They can add up with rims, caps, trim rings. 15x8 or 16" waggons ("styled steel") are an option too. I do wish there was a 15x8 or 16" steel option to run dog dish caps for the 6-lug trucks. I'd like to run 31" or 32" BFG T/As or an E rated 16" tire.

U-joints this weekend. Hopefully I've ordered the right parts. Not sure I'll mess with the CV joint this go-round. But the deep hum-rumble-vibration that shows up between 45-50mph is pretty disconcerting. Hope this solves that. Then I'll feel pretty damn fine about the mechanical condition of this truck.

Cruise control is on the bubble for the near term. I commute 275 miles round trip once a week and cruise would be nice on the highway. It's all there and seems like it will work. But when the GM crate 350 went in, they skipped the cruise transducer with the speedo cable. Went right from t-case to speedometer. So need to figure out part numbers for the two cables. Should be straight forward.

Anywhere I can turn to educate myself on the NP203? I really don't have any experience with this full-time 4WD and lots of people have mentioned swapping or converting the t-case. Need to educate myself.

Fun stuff, eh? Thanks for the comments.

R

[Katrina/10]

You could run the rally wheels without rings and caps, it doesn't really look bad that way. I don't know of an 8 inch wheel that accepts stock caps, but there may be something out there. The cruise may have been bypassed because it didn't work, only one way to find out. It's just an ordinary speedo cable in and out, you may be able to find some generic ones that will work.

The 203 has an internal differential to allow you to drive on pavement in 4wd. But, if one wheel totally loses traction, you can get stuck. That's why the shifter has the lock position, it locks the front and rear axles together for more traction. There are part-time conversion kits out there, not sure how complicated the installation is. Lots of reading on the four wheeler boards.

[RyanAK]

LOTS of reading about the 203 on the 4-wheeler boards. Sheesh! That's not really my application, so I guess I'll take it with some salt. I do get some tire scrubbing in parking lots and the truck doesn't really coast like a 2wd or a part-time 4wd... but otherwise, is a conversion really worth it? Will there be any appreciable gas mileage improvement? Will the truck eat front tires without? Will my front end and t-case blow to smithereens if I don't slam in a conversion or swap to a 205? Hmmm....

I haven't been able to find a 15x8 or a 16" wheel for 6-lug that will accept the stock caps and I've been looking consistently since I realized that the stock wheels are 15x6 and I'm maxed out at a 29" tire. 235/75R15s. Actually... Wheel Vintiques makes a 6-lug OE-style 15x8 steelie that'll take the caps, but shipping is gonna be harsh.

[AJC]

The NP203 is not as bad as every one makes them out to be. One plus is it has a better low then a NP205 (2.73 vs 1.96). They are picky on the oil used in them. ATF is to thin and gear oil two thick. It takes straight 30 weight as a lot of the chain issues come from using the wrong oil. As with any AWD vehicle the tires will need to be a matching set of 4. I ran a set of 10" wide rims on a truck with one and they wore the tires much faster then the narrower tires on the 7" or 8" factory rims. Also I wouldn't go bigger then 31" tires if running a 2.76 or 3.07. Check your SPID. If your NP203 is in good working order I wound leave it as is.

Also you should be able to get the Wheel Vintiques rims from Summit Racing and if the order is over $100 dollars ground shipping is free.

[RyanAK]

Thanks, AJC. I appreciate the info. I knew to use straight 30 weight, and will definitely run a matching set of 4. I'm only looking to go to a 15x8 or a 16" wheel. Not 10" wide. 3.73 gears so figured I was good with 31"-32" tires. With a 31", I'd get under 3000rpm at 70mph on the highway. 32", a bit less than that.

Does the AWD feature of the NP203 limit it as far as highway driving?

16" rims would get me an E rated tire.

Summit currently only has the 15x7 Series 62 wheels listed. That would get me on 31x10.5-15 rubber. Could always go rally wheels or wagons...

[RyanAK]

Been trying to devise a strategy for dealing with the surface rust that doesn't involve a full re-paint (yet) but doesn't look too crappy... I think whatever needs addressed on the tan paint should be pretty easy to to address and blend in. The upper red, however, is pretty oxidized and I'm not sure how to approach that and not have it look like a patchwork...

[RyanAK]

Kids like it!!

[AJC]

Nice that you got 3.73 gears. Makes it easier if you ever go to an overdrive transmission. The NP203 should handle highway driving just fine but proper lubrication is key. Even the part time kits recommend driving in 4 high every couple hundred miles to make sure the front of the transfer case gets proper lubrication. So at least with a full time you don't have to worry about that.

Bummer on Summit not having the right size rim. You could go to rally wheels but I dig the hub caps.

I would try buffing the paint to get closer to the original paint color. It should also help with paint matching. You can do it by hand or machine. Just be careful about not rubbing through and test somewhere inconspicuous first. Like the roof.

[RyanAK]

3.73 gears seem just right for the way I use my trucks. I’ve had 3.73s in most of them since I was 16. I don’t anticipate ever going to an OD tranny, but you never know.

I’m up in the air about the full-time or converting to part-time. I’m good with either, just thinking on which set of options would be most useful for me. Is 2wd important for the kind of driving this rig will see? Or is the AWD more useful? Would losing the AWD and only having 4 High Lock be ok? Hmmmm... stuff to ponder.

U-joints in the morning. Probably gonna kick myself for not doing the CV at the same time, but I couldn’t source the ball kit to arrive in time. Ah, trucks!

R

[Old65C10]

One thing to think about is how you use it. Will you drive it in the snow? Will you be using it for any serious 4x4 duty, or just light stuff like forest service roads?

For light duty stuff, and snow, the AWD full time is just fine and can be better than the part time set up. However if you plan on getting really serious then the part time conversion is a good plan.

I also just got a new Suburban, a 90. It is a 3/4 ton 4x4 and has a part time case factory. I lucked out and got a LSD in the rear, so I plan to leave it alone. It will see light duty off roading and snow.

I also had to order tires. I struggled with the same issue as you. I want the stock steel wheels with caps. It currently has 20in rims on it and they suck.
In the end I ordered some all terrain stock size load range E.

Good luck with you project, I will be interested to follow as you continue to work on it.

[RyanAK]

U-joints. Ugh. 5 hours to get the front replaced. Rears are going much easier. Should have done the CV while I was under the front...

Yeah, snow and forest service roads. No “serious” 4x4ing. Just average country family 4wd situations. Sounds like the full-time AWD will be fine for that. I guess that leaves the highway miles... which I will guess will be fine with the AWD rather than 2wd.

I saw your ‘90 ‘burb posted. Glad you’re not keeping the 20s. 3/4 Ton 8-lug will get you an OE-style 16” rim so you can run stock caps and E load range all terrains. Wish it was as simple for 6-luggers. 15x8 would be ok, but they aren’t currently in stock.

New issue. Cab and tail supports too far gone to pass Pennsylvania state inspection. Ugh. Guess the truck will sit until I have the cashola to get that fixed.

[AJC]

How bad is it? The outside looks pretty good, are the cab supports rusted though?

[RyanAK]

They’re pretty bad. Outside has had some work... new rockers, some pretty good bondo work. (Who goes through the trouble of replacing body panels but not the structural parts?!) Fronts seem straightforward, but the rear is gonna be a bear for the body man. I didn’t think this would keep the truck from passing inspection. It’s in such good shape otherwise. Apparently no inspection in Montana.

Kids are sad. Body guy can’t get to it until mid-September at the soonest.

[AJC]

Well that sucks. Guess it gives you some time to work on other things. Are you going to track down some factory rear 3 point seat belts or do you have something else in mind? Because with kids back there and how unpredictable others drivers are today; it's better to be safe than sorry. I can keep an eye out for a set if you want.

We have no inspection here in MN. Which is good as my drive side floor in my K10 is an old campaign sign. And if we did have inspections at least a quarter of the vehicles wouldn't pass due to how bad rust is here.

[Old65C10]

I am surprised that it has rust that bad, it looks great from the outside. There are many many states that do not have an inspection. Oregon, Washington, Idaho, Montana, even Calf only inspects the emissions as well as Arizona last I knew. California and Arizona may have changed, but I when I lived there, all they did was check the smog equipment and at that time used a go-nogo gauge for the fuel tank. Back when we could still buy leaded gas.

[RyanAK]

They’re pretty bad and they’re on my list to fix when I get into bodywork. The body panels are pretty good replacement and decent body filler work. Pennsylvania has become militant about rust during vehicle inspections. But the state contributes in a huge way by salting and spaying god forsaken BRINE on the highways.

I get inspection for tires, brakes, frame rot... I didn’t expect this. And Spencer and Nora are chomping at the bit to take daddy’s truck on a “venture”!