[1970cstblazer]

Originally Posted by special-K

You show the same thing I showed. I'm trying hard to see how you get out of that the 68/69 knobs are red plastic. It's the '70s that had red plastic and their part # is the same as the blue 71/72s. GM parts is not a restoration business, it's a replacement part business. They will supercede a part with one that works if the original design is depleted from stock. If the 68/69 hub assemblies listed are red plastic with chrome retainer rings, it could be that GM had Spicer make a batch so they could continue providing replacement parts to comply with the law that requires mfgrs to provide replacement parts for 10 years. And since Spicer changed the design, they would have made new assemblies to work with the closed knuckle Dana44s in that design. I do know, from my experience of dealing with and owning these 4wds, that from the factory the '69-back K/10s came from the factory with the metal Spicer hubs. I have never owned a '69 blazer and never been well acquainted with one, I can say that. I believe it could be possible that the Warn (GM misprint) semi auto hubs are what came on '69-only Blazers and those would be Warn's Loc-O-Matics. They would interchange with the K/10 hubs as a replacement. Those came bronze with red painted in the recessed area. The most original '69 Blazer pictures I have found show the knobs as yellowish, certainly not red, and they aren't the design as the plastic ones. My guess is those are the Warns with the red paint gone

As far as GM superceding a newer design part in place of the original design due to depletion of stock, Have had experienced that many times. I remember I got all excited, in the early-80s when I began ordering still available 67-72 parts, when the parts guy found the 69-72 steering wheels were still available but only in black. I ordered one, it came in, and it was a '73 style wheel. I've had it happen over and over again. I have bought front wheel bearings for a '71 K/20, way back then, that had "Made In Japan" stamped into the race rim. I am willing to accept that somehow I never saw or owned 68/69 that came from the factory with plastic hubs before if I see proof. But in my years of dealing with these 4wds parts I have had more guys than I can count asking if I had the original all metal Spicer hubs for their pre-70 K/10s

SOME 1970 K10'S/K/5'S with F76 had the red knobs. ALL 1970 K20 with F76 had the red knobs.

The October, 1968 parts book which also covers 1969 models shows 3937068 red plastic knob, which was changed to 3979551 blue plastic knob in 1/1971 per the 1/73 parts history book. That's why you will see the later parts books specify 1968-72 using the 3979551 blue knob.

I have shown MANY examples of 1969 Blazers, which used the open knuckle drum brake Dana 44, with red knobs.

I have shown MANY 1968 AND 1969 K10'S with closed knuckle drum brake Dana 44's, also with the same red plastic knobs as the 1969 Blazers.

Many GM parts books show 1968 as the transition year to the K/10 Dana/Spicer locking hubs that utilize the plastic hub knobs. Many of the internal hub parts interchange from 1968-1972 and even later than that!

As was shown, 1968 and 1969 also used the "Warn" semi lock hubs, so it appears either was used.

See older thread:

https://67-72chevytrucks.com/vboard/...d.php?t=251398

Also:

Originally Posted by MJN

The parts catalog shows #3979551 for 68-70 K10. 6259019 is the knob for 73 and up yellow K10/internal style lockout hub. The red actuating knob in my OP is for K20 (3/4 ton) hubs not 1/2 ton hubs. Based on the parts catalogs they used the all metal external type hub lok on '69 and older K20's and '70 was the first year for the red plastic dials for K20 external type Hub lok's.

Some additional digging I found the Dana part # 34916-3 (GM#3979551) was preceded by Dana 34916-1 (GM #3937068). GM 3937068 shows for '68-69 K10 & '69 Blazer with 350 only. No color is listed however. The only notes in the parts catalog related to the color of the actuator knob are for K20 series hubs. The later yellow K10 knob (6259019) was Dana # 34916-4.

https://67-72chevytrucks.com/vboard/...d.php?t=809746