12 bolt rear & 10 bolt front rear?

[wells]

I just bought a 1983 K5 that has a 12 bolt rear and a 10 bolt front rear. Was this a common oem setup?

 

[MTBLAZER89]

The 10b front is probably stock, but they started phasing out the 12B around 80ish. With these trucks nothing is definite when it comes to what the factory did, but for the most part No the 12B rear is not stock.

Previous owner probably thought it was a significant upgrade.

 

[wells]

Thanks, I guess a lot can happen in 189,000 miles.

 

[76zimmer]

Thanks, I guess a lot can happen in 189,000 miles.

Yeah, he probably went through a couple 10's and found a 12 to put in it.

 

[AJMBLAZER]

GM was using those up intermittently for years but '83 is pushing it.

 

[diesel4me]

My '85 K-10 Suburban has a 12 bolt rear,sure "looks: original too,but who knows...it has 160K on it so it might have blown its 10 bolt long ago,if it ever had one..I have seen quite a few 1980-1986 1/2 tons that had 12 bolt rears,and some were one owner trucks and they swore nothing in the drive train was ever changed!..I always thought GM only used them up to 1980,but I guess not?...maybe they had some leftovers to get rid of,most of the trucks I saw them in had higher GVW's than the ones with the 10 bolt axles..

 

[tRustyK5]

My old '81 Jimmy had a 12 bolt stock, but it was a 4 speed truck.

GM was so weird with stuff like this, you never know what you're gonna find sometimes.

Rene

 

[496truck]

I dragged home an 87 Burb for parts, 1/2 ton with 3:73s and a 12b rear.
Certainly looked original, but with that much rust, who knows.

 

[AJMBLAZER]

Think about it this way - as far as D44's and 12 bolts showing up later than they "should have" - GM was using up the stuff they had sitting around. Lots of warehouses, that was before LEAN/6 Sigma, racks of stuff sitting around, stuff in the production system at the part maker, etc. Meanwhile smaller body parts or trim pieces could be returned to suppliers or sold to wholesalers/distritubors to get rid of them. Axles...not much for NOS today and then they knew they were getting rid of them entirely so just use them all as they receive/find them. Once they ran out of the parts needed to install them then they'd be scrapped/sold off.