I wish it were that easy. Lol. Finding one is the problem. Nobody has over locally. I was lucky enough to find this one. I know brewers has them, I guess.
Just get an A Body main shaft and tail housing and swap everything over. Hemi boxes have bushed gears and the B Body Hemi main shaft is hardened, you can sell that at a premium price. Tail housings are a wash as far as price goes. That is how I got my Hemi A Body trans.