Here is a link to a quick video of the truck in its current state. I plan on taking lots of photos during the build to keep you all up to date.
http://www.youtube.com/watch?v=Jae4KzxjmbI

 

Nice truck. Gotta get line locks so you don't have to wear out the rear brakes while you do a brake stand.

 

The 8.5" 10 bolt is not a myth. It's not something I've read. I have worked for a Chevrolet dealer for over 10 years. Over that time I've seen many of the "W" code 5 speed second gen's come in and every one of them had the 8.5" 10 bolt. I've also prepped some of them when they were new back in the days when I was still a tech in the service department. As for the ZR2's, if you've seen one without an 8.5" rear it was a 4x4 that someone bought stickers for. The locking differential wasn't standard in the ZR2's, but the 8.5" rear was. With any good parts in the 8.5" it's going to live to well beyond the power most street driven trucks (well into the 10's) are going to run. If you'd like some proof I can get you vin's including pic's of two trucks that my friends personally own with the 8.5" diff. They may be more difficult to find, but if a chevy part is available, why not go with that. The wheels, breaks, everything bolts right up.

With good parts the 7.625" rear could hold up to most 5.3L builds as long as it's an automatic.

 

I will add to your myth theory. Go to a GM parts counter and ask them to look up group 5.386 and you'll find the listings for the axle assemblies. If you'd like I can print and scan them here for you. You'll find that the L35 with the M50 transmission came with the 8.5/8.625" 10 bolt only. They were 3.08 gear in the pickup and 3.42 gear in the Blazer (2dr only).

 

Yup, Zippy is 100% correct.

 

Well it looks as if there's no changing your mind in this matter because you have a computer in front of you to look this info up, so I'll just agree to disagree with you because ya can't beat first hand experience looking at the axles yourself still in the trucks. Maybe they just aren't as common in MN because most of the trucks around here aren't lowered 2wd's with 4.3L 5-speeds...they become snow plows in the winter.

At any rate the 8.8 is still my suggestion for best money spent.

 

Well it seems that the 8.8 would be able to handle more power, but for my application the 8.5 will hold up fine. So im going to keep it all chevy. Any suggestions on a reliable and not too expensive 5 spd? Currently the truck has a 700r4 and it would be really nice if i didnt have to get the driveshaft cut again or a whole new even.