Possible to build a solid 8.25" ?

Carrier is the differential. If you are going to look for parts from a truck be aware that 97 and newer 8.25 rear ends in the trucks use 29 spline axles and your rear end has 27 spline.

I had picked up a 8.25 a couple of years ago for my Barracuda. It had 2.9x gears and a sure-grip. I rebuilt it with 3.55 gears. I got the ring and pinion from Randy's and a master overhaul kit (all the bearings and shims) the cost was just a little over $200. I have since seen adds that would suggest that you could get the parts for under $200. Also, I have seen the Tru-Trac style sure-grip like the ones that come in Dakota's for less than $200. Just another option to trying to score parts from the junk yard.