Here are some pics of the s-10 rear end that I modify to fit under my vette. 
I have made one axle,These 2 axle was on the same rear end,the one with 4 nut have been modified,turned,welded and drill.Now I have a s-10 axle,bigger than the chevette,with 4x100 bolt pattern
You can see the difference between chevette and s-10 modified axle,same lenght(not modified) 
It's the housing,The chevette tube are in the s-10 tube.Very easy to do,chevette tube outside diameter: 56.00 mm, s-10 tube inside diameter: 56.10mm.Just cut the 2 housing,insert the chevette tube in the s-10 one and it's done!Adjust width with axle and weld it on place.very easy to do!
Posi gears,3:42 ratio,ring and pinion are from a 83 s-10,posi system from a 87 s-10 
Some pics of the rear end,just before installation.The chevette factory tube is replaced with the "tube" you can see.Fit like factory under the car
Pics of the rear end installed..! 
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