72 Demon slanty-to-340 Resto

8 3/4's aren't that bad as long as you avoid A-body housings.

With a Demon you can use a B-body 8 3/4 and those are half the price of the A-body 8 3/4's, and everything's already big bolt pattern. Until I bought an all brand new 3rd member a week ago, I don't think I had more than $500 in any of my 8 3/4's, and I've got a bunch. I think the most I paid for a B-body housing with axles was $250 (no 3rd member). I paid $65 for a bare E-body 8 3/4 housing of all things from eBay just last year, and that was shipped!!! Most of the used stock 8 3/4 axles are like $100, just need new bearings (again, non A-body). And for a few years there were frequently 8 3/4's in the pickNpull's around here, they were like $160 drum to drum on sale so I have a few. The 3rd member in my Duster right now was out of a truck at picknpull. Pulled the whole 8 3/4, dropped the chunk and cleaned it up a bit, installed. Been running it for thousands of miles now. The 489 with 4.30 gears I just bought from Dr. Diff to go with my T56 swap will be the only new one I have, the rest either came with one of my cars or out of a yard, no rebuilds, all original.

Honestly I wouldn't build an 8.25. If I found one I might run it as is, but I never saw an A-body 8.25 in the yards here in 10 years of looking. B, C and truck 8 3/4's, and a few F body 8.25's, but nothing A-body other than 7.25's. If I was going to do something other than an 8 3/4 I'd go with the Ford 8.8, you can get those from the wrecking yards, usually with pretty decent gear ratio's and they have disk brakes. You can do the trick where you shorten the long tube to match the shorter side and grab an extra short side axle from another exploder. With a Demon you can just run it as is too though. If you shorten the "long side" to match the short tube they're 56 3/4" wheel mount to wheel mount, and in original form they're 59 3/16", which is still shorter than the 60.125" 68-70 B body 8 3/4 I run. Here's a good thread on the 8.8 8.8 swap I would use some kind of jig to shorten the tube, but that's just me.