its worth saving. in my opinion. a core is worth about 100 bucks. what gears are in it? ill take a dana any day over an 8 3/4. cost to build is close to one another, and its way stronger. you dont have to worry about paying 200 bucks for an 8 3/4 a body housing that can be bent or slightly tweaked. there are several posts about making a truck dana fit an a-body.
danas are stronger but alot heavier, even though the weight is where you want it, it rotating weight that kills you, it you are going to do a full build on either one- narrowing, custom axles, bearings, and complete center- if you build it right, an 8 3/4 will stand up to as much torque as you can through at, if the rear end is much stronger than you need it, that just means that its more rotating weight,
i scored an complete 8 3/4 for $100 and sold the center section out of it for $125, so i got a return on my investment and a free housing, if your planning on narrowing it anyways, dont worry about which width you want, if you look hard enough, anything is sitting in somebodies barn
a dana in similar size with similar brakes as an a-body 8 3/4" is 50 lbs heavier. most of it is housing wieght. huge cast center compared to the small chunk of an 8 3/4, and 3/8" axle tubes vs no more than 3/16" on the 8 3/4. you will see no loss in performance swapping from one to the other as we have tried both in the same car, dana will handle much more power than an 8 3/4. but i guess 50 lbs is 50 lbs, and if you dont need it then dont use it. but id take it. why let it slip away when it is there free. chances are it is 3.54, maybe even 4.10. you can buy a brand new clutch type posi for around 285 bucks, if the gears are quiet, use em aas is. have it narrowed and buy some good axles. for less than you can buy an a body 8 3/4 small bolt pattern, stock axles with a sure grip chunk, you will have a way stronger rear with good aftermarket axles. if you need it narrowed i know a good guy local that can chop it, weld new ends and perches, with a fixture.