axle difference in 1988-1998

[MarkZ28]

My 89 c1500 has 30 splines in the stock 10 bolt. Im sure its the original rear but no way to tell. it has the corect 2.73 ratio with no locker. Maybe it was a late production truck that got the 30 splines. I removed the axle shaft to verify it has 30 splines also.

 

[98chevy2500SS]

The only difference in 3500s was that the 88-92 were extended cabs in the GMT400 and the 88-92 were crew cab square body's. Just like the 99-00. They did the same thing. Crew Cab GMT400 99-00, GMT800 3500 Extended Cab 99-00. I could be wrong though, but that's I have seen. GM did this again on the GMT900s, up until late 2014 when the upgraded body style came on the 3/4 ton and one tons for 2015. I hope my post makes sense, kind of hard to explain this without doing this on paper and writing everything out in categories lol.

Sorry for being off-topic, just thought I would say this.