Technically, you already have since someone tagged me but specifics should move to PM so you don't violate the forum rules. I am an hour from Seattle on highway 2 and can take a look at what I have this weekend.
The local wrecking yards with squarebody parts would be Budget truck wrecking in Auburn, Braven Auto and Metals in Lake Stevens, or Pick n Pull in Arlington.
You will have a Spicer 1350 joint at the rear axle as that was what came with it from the factory. You could have Spicer 1310 or 1350 at the Tcase depending on where parts came from. I would measure the two u-joints to verify if they are the same or if the front is smaller, either measuring width across or diameter of the cap. If they both match, then the 3/4 ton shaft that you shorten and balance will probably run you around $200 by the time you finish not counting new u-joints.