Rear End Swap

[Steppin67]

I have a 1967 C10 with an open rear differential. I wanted to swap to a posi rear end. I found a 1990 Silverado with a G80 rear end the question I have is can I take the chunk out of the 1990 Silverado and put in my 67 with changing the whole rear end?

[Bigdav160]

No. The 12 bolt (8.875" gear) parts do not interchange with a later 8.5" gear

[Steppin67]

Thanks. Any advice on how to swap to a posi without breaking the bank?

[polishspy]

find an older (73-84) rear end with a posi like a 14bolt, may have to weld a new shock mount, but the rest should fit.

[kwmech]

Forget the G80 crap, suck it up, save some money and put an Auburn in it. You'll be ahead in the long run

[57taskforce]

Originally Posted by kwmech

Forget the G80 crap, suck it up, save some money and put an Auburn in it. You'll be ahead in the long run

Exactly right, the g80 has the nickname gov bomb for a reason.

[Ironangel]

Originally Posted by polishspy

find an older (73-84) rear end with a posi like a 14bolt, may have to weld a new shock mount, but the rest should fit.

With all due respect, Totally BS! No C/10 EVER came out of the factory with a G80! Period! Your 1/2 ton 67 most likely has a 12-bolt. The G80's were not only reliable but second only to the "Detroit Locker" that were ONLY available in the 3/4 & 1 ton 14-bolt axles so get it right! The 1-ton G80's were impervious compared to the "1//2 ton Gov Locks!" Know WTF your talking about before you stick your Chinese made size 10's in your mouths! The 69 C10's had factory 12-bolts, 12T's as opposed to the car 12p's (T=Trucks P=Passenger cars) Now on to the answer...Buy a 12T Eaton Posi, install your current gear set, and enjoy one of history's greatest mechanical differential milestones ever...The 12-bolt truck Posi! No cheap way out! 470$ for a Legend! All that G80 talk is BS because first of all, you don't have one! Second of all, most the schmo's that said they're no good? Never had one! "Just Sayin!"

[Minkota]

Originally Posted by polishspy

find an older (73-84) rear end with a posi like a 14bolt, may have to weld a new shock mount, but the rest should fit.

I thought the 67 had Coil Spring and the 73-84 had Leaf Springs?

[Grumpy old man]

My 95 GMC K2500 has it's second G80 in it the first one lasted over 200,000 miles of working ,Hauling heavy loads and pulling trailers all over the south east , It finally let go while I was delivering a short bed from eastern NC to another member in Nashville . I limped it home and I already had another rebuilt carrier sitting in my garage because I knew it was on it's way out but I thought I could get one more trip out of it , Nope .

The local parts houses wanted $750.00 + for the G80 ,I found one on Ebay for $299.00 and it's been in there for 5 years now .

6 years ago I was buying clean short beds for $4-500.00

[72c20customcamper]

Originally Posted by Ironangel

With all due respect, Totally BS! No C/10 EVER came out of the factory with a G80! Period! Your 1/2 ton 67 most likely has a 12-bolt. The G80's were not only reliable but second only to the "Detroit Locker" that were ONLY available in the 3/4 & 1 ton 14-bolt axles so get it right! The 1-ton G80's were impervious compared to the "1//2 ton Gov Locks!" Know WTF your talking about before you stick your Chinese made size 10's in your mouths! The 69 C10's had factory 12-bolts, 12T's as opposed to the car 12p's (T=Trucks P=Passenger cars) Now on to the answer...Buy a 12T Eaton Posi, install your current gear set, and enjoy one of history's greatest mechanical differential milestones ever...The 12-bolt truck Posi! No cheap way out! 470$ for a Legend! All that G80 talk is BS because first of all, you don't have one! Second of all, most the schmo's that said they're no good? Never had one! "Just Sayin!"

He didn't say his c10 had a g80. He asked if the 1990 g80 posi would work in his differential.

[kwmech]

Originally Posted by Ironangel

With all due respect, Totally BS! No C/10 EVER came out of the factory with a G80! Period! Your 1/2 ton 67 most likely has a 12-bolt. The G80's were not only reliable but second only to the "Detroit Locker" that were ONLY available in the 3/4 & 1 ton 14-bolt axles so get it right! The 1-ton G80's were impervious compared to the "1//2 ton Gov Locks!" Know WTF your talking about before you stick your Chinese made size 10's in your mouths! The 69 C10's had factory 12-bolts, 12T's as opposed to the car 12p's (T=Trucks P=Passenger cars) Now on to the answer...Buy a 12T Eaton Posi, install your current gear set, and enjoy one of history's greatest mechanical differential milestones ever...The 12-bolt truck Posi! No cheap way out! 470$ for a Legend! All that G80 talk is BS because first of all, you don't have one! Second of all, most the schmo's that said they're no good? Never had one! "Just Sayin!"

You're saying this --tongue in cheek right?--- I just about pay my rent replacing G80s b-cuz they explode inside the diff destroying the cover and ring and pinion in both 1/2 and 3/4 tons. Never seen them in a 1 ton. Occasionally when they blow they will even bust an axle shaft when everything locks up. OP was talking about replacing his 12b with a 10b. The 3/4 ton g80s do not come apart as often as the 1/2s, but believe they do, and when they do the destruction is quite impressive. The past year or 2 the amount of them blowing up has seemed to slow down. I think it is because I may have replaced them all within a 1-200 mile radius in the past 20 years

[michael bustamante]

the 67 chevy does have coils. but leafs were an option.
if he were to go with a 73 square body rear, of course he would have to weld on new mount plates where the trailing arms attatch and cut off the shock mounts as the lower shock mounts are plates under the rear end mounts. also he would have a 5 bolt in the rear and 6 in the front till he does a disk brake swap. this is the most common thing to do.
67-70 rear ends with posi are out there for sale if you are patient and look or do a WTB on here if youre a paid subscriber. Grumpy probably has about 4 or five stashed in his sheds! LOL.
If you don't want to convert to disk yet I would look for a 63(?)-70 trailing arm posi rear end as its a direct bolt in

[Grumpy old man]

[QUOTE= Grumpy probably has about 4 or five stashed in his sheds! LOL.


I have a few stashed away

No, They are not for sale .

[michael bustamante]

[quote=Grumpy old man;8564773][QUOTE= Grumpy probably has about 4 or five stashed in his sheds! LOL.


I have a few stashed away

No, They are not for sale . [/quote]

I knew it! youre a hoarder like me!

[57taskforce]

Originally Posted by kwmech

You're saying this --tongue in cheek right?--- I just about pay my rent replacing G80s b-cuz they explode inside the diff destroying the cover and ring and pinion in both 1/2 and 3/4 tons. Never seen them in a 1 ton. Occasionally when they blow they will even bust an axle shaft when everything locks up. OP was talking about replacing his 12b with a 10b. The 3/4 ton g80s do not come apart as often as the 1/2s, but believe they do, and when they do the destruction is quite impressive. The past year or 2 the amount of them blowing up has seemed to slow down. I think it is because I may have replaced them all within a 1-200 mile radius in the past 20 years

Yep and if your real lucky it just kills the governor without blowing the whole thing to pieces, they are junk, I don’t care what anyone says.

[cornerstone]

Originally Posted by kwmech

You're saying this --tongue in cheek right?

I'd like to think so, but I'm guessing not.