Unless you can find one from a Gbody that someone has built, you'll have to do some mixing and matching. I believe that all the S10s and baby Blazers used Gov-Locs if they were limited slip. It's more of a locker and they are also 28 spline. Some guys like 'em and some guys hate 'em. I have no opinion on the Gov-Loc but I think they are designed for more of an off-road than a street situation. They had a wide range of gearing. The (pre-'88?) Camaros/Firebirds used an Auburn clutch-type limited slip that were 26 spline but had tall gearing like the Gbody. I think the '88-up were 28 spline but gear selections were a bit better. Gear selection is totally up to you. I think with your Olds 350 a 3.23 or 3.42 would be a good choice as a driver. I'd save 3.73 and 4.11s for track cars.
My combination was 3.42 gears out of a Blazer, Auburn limited slip from an '87 Camaro, Speedway ring gear spacer and install kit. I got the used rearend parts on 1/2-off day for $75 and sold the Gov-Loc from the Blazer on CL for $75. That made my parts cost = zero. The ring gear spacer and install kit was about $120. Be aware that the earlier (pre-'81) Gbody used a smaller pinion bearing.
