Okay then ;
Here's where the fun begins : now you need to begin chasing the Hot Rodders as they typically just toss the stock parts under the bench out out behind the garage and there they sit unwanted and hard to sell, heavy and bulky as heck too so often you can contact someone who built their Hot Rod years ago and they'll be happy to give you the old engines, trannies and so on...
Or, sell for scrap value .
If you go to car shows, coffee & cars gatherings or swap meets, make a simple sign out of an old biscuit or cereal box saying "WANTED OLD CHEVY REAR END OR BRAKE PARTS, take along a pad and pencil as you will be MOBBED by people desperate to get that old junk the heck out .
Some here needed good used 216 / 235 engines and got them for FREE doing this...
I wish you the best of luck in beating the bushes, maybe Joe will take pity on you and sell you what you need .
I'm not on facebok but if you are they have a big vehicle section, put up a 'wanted torque tube rear end' notice and you'll polly find one near you .