Where do Shastas usually rot?

A '64 Shasta any model should be the canned ham shape. The water will run along the curves to the bottom, and the worst of the rot will generally be at the base of the 4 corners. Around the door frame and wheel wells, the skirt boards will need close inspection.

Of course if it has sat uncovered and unattended for years the tape along the whole seams would be suspect, and the seepage can show up in the corners of the ceiling and wall, especially in the rear above the bunk. Beneath the windows, rear window and especially the side fixed windows over the dinette seats will also be bad spots, generally speaking.

Schweet really did hit the nail on the head. Rot will be easy enough to detect. The real "hunt" would be for typically rotten spots that are not. The more of these you find the faster you should tow it home and ask questions later.

I don't even need another trailer, but I thought that if it was fixable I would pass the info on to this everyone here.
Is there any parts that are hard to find that I should look for. I may get it and sell it for parts.

A working propane refrigerator.

If you decide that parting it is the way to go, I am still looking for a complete rear window assembly...the push-out type.

What model is it?

How do you tell what the model is? Any markings on the outside?
I will get some pics of the door lock, rear window and any gas lights.

By 64 they had fixed the solid side dinette window problems by eliminating the solid side front dinette windows. However even the Jalousies will leak if they are not pulled and resealed in time. Because of demand, I wouldn't part out ANY Shasta now. Even if it's falling apart just sitting there it's a valuable item.