1978 "Big 10" rear end question

[72timemachine]

There is a '78 c/10 big 10 a few hundred miles south of my location that has a 5 lug rear axle. I would imagine it is a 12 bolt rear end if it is stock, no?. Aside from this special truck having beefed up suspension, does anyone know if GM gave these trucks limited slip rear ends or was that an option you had to have the dealer order for you back in the day? Any help would be appreciated.

[Matt Man]

Originally Posted by 72timemachine

There is a '78 c/10 big 10 a few hundred miles south of my location that has a 5 lug rear axle. I would imagine it is a 12 bolt rear end if it is stock, no?. Aside from this special truck having beefed up suspension, does anyone know if GM gave these trucks limited slip rear ends or was that an option you had to have the dealer order for you back in the day? Any help would be appreciated.

2wds got the 5 lug while 4wds (halftons) got 6 lug wheels. In 1978 the rear axle should be a 12 bolt but many swap it out to a later 10 bolt rear axle 12 bolt axles were last used in 1981. The limited slip rear end would be optioned as code "G80" which was not a good unit in the half ton trucks. Here is a picture of my SPID label which states the limited slip G80 rearend.

[72timemachine]

Fantastic, thanks for the information. Yes, I am starting to recall that G80 code.

Tell me one more thing if you're aware. Did GM use this code for several years on trucks and vans. I know vans came with some limited slip rear ends and some times I find them in the junk yards and read the build sheets under the hood to see if it has a limited slip carrier. I know the axles are too wide for a pickup but that would be half the battle in building one.

Thank you.

[78 Big10 454]

No complaints with the limited slip in my 78. Glad to have it with a 454.