A body 8 3/4 posi rear end bbp

Do you need everything? Like ready to bolt in.
I have one; narrowed, with perches moved in for the Mopar offset hangers. Yes 5on4.5 axles shortened and resplined. Your choice of 2.76/2.94/3.23/3.55, And yes a reconditioned cone-type SG, preloaded to 120ftlbs turning torque. These will not be 2881489s. You can specify large or small yoke.
The rear is still under my FormulaS. It accepts 15 x 10 rims (also available) with a 4.5 bs and fits inside the stock Barracuda tubs. It is not currently leaking. I could reseal it for you. The 3.55s are slightly noisy,and have been for over 10 years. It's not a bearing noise, and it's not a pattern problem, it's just the way it is,lol.
It will not bolt into your Demon unless you move the springs inboard.

I can also supply a totally stock complete rear end, but the axles will be 5 of 4" bolt circle, and with tapered bearings.
Both can be had with 10" backing plates installed.

PM me if interested.