A couple of things to note on that frame and chassis are that the '60-'66 chevy 4x4 frames were built out of the same dimensions as the 1 ton frames from that era, so those frames are good. If you end up swapping to a newer frame like a lot of people do, don't crush it. Someone will pay good money for it.
The bellhousing crossmember, or rear engine mount crossmember (same thing) is that piece that's bolted to your bellhousing. Those are rare. Don't throw it away. Sell it if you aren't going to use it. However, I would suggest that you use it with a v8 bellhousing. It will locate the engine in the stock location, and give a little added frame strength.
As for transmissions, I will heartily suggest you put a gm 2wd NV4500 behind the 350 and keep the divorced transfer case.
The later axles are a good swap since you don't have to modify anything to bolt them up. If you were closer, I would take the original rear axle off of your hands. A lot of those rear axles were made, but not many had the spring perches in the location that yours does.
Check with Captain Fab over at 67-72 chevy trucks for brake booster and brake and clutch master cylinder brackets that use your stock pedals and hydroboost brakes. He also makes a bracket to bolt up later model steering boxes. He makes good stuff that usually will bolt up without any real modifications to get you power steering and power brakes. If you get rid of your original steering box and bracket, don't trash it. Someone is searching for one.
In general, about everything on that truck is rare. Don't trash any of it because someone is looking for it.
That's a great truck with a cool history.
