On Wednesday I removed the rear drive shaft from the other truck.

I was immediately aware that the rear uni joint was different to those I have already installed on front axle prop shaft and shaft from gearbox to transfer case. The locking of the uni joint ends are on the inside of the cups, nearer to the uni spider. All the others lock on the outside of each cup. Is this even for a Ford? Doesn't look like anything in the manual. Is the rear shaft same diameter tube as front? This one is, but I would have expected thicker than front! If this thing is NOT Ford, then I am in trouble again. I have a badly butchered piece of thicker shaft, which had been cut to about 3'. It has a uni (larger than front ones) on one end, but I don't believe I have the other section. Just another example of getting incomplete parts from the guy I bought the truck from.

This is the different type of uni that was on one end of the narrower shaft. That one was complete, but too long (expected that) and will not attach to the coupling part on rear diff.
On another topic.

The radiator is temporarily in place. It's only there because that is probably th safest place for it to be. If I put it back into storage, it would be likely to become damaged.