My build date is 9/69 also and the prior owner was using a screwdriver to turn the electrical. Wish I could find the key portion, especially after seeing that pic.
Most of those universal switches are about the same and I had the same problem that you are having with 2 different ones. As I recall, the inner nut that doesn't show and the nut that is on the outside of the dash neither had a good surface to "bite" the dash and prevent turning. I remember...
I called it a vinyl tubing to best describe the fact that it is not heat shrink and to compare it to what Pete described as flexible conduit. It is thicker, and slides freely except where the wires exit and there it is crimp sealed.
Everything on my 69 was black electrical tape however most new OEM lamp assemblies pigtails had a vinyl tubing on them sort of sealed near the connectors.
Those things are rare here because of rust but recently I have been seeing one around that is repainted the original 2-tone colors with everything else basically stock. That 2-tone color scheme really sets the early ones apart.
Something about the phrase "frame on restoration" sounds like a paint job to me especially with no underhood pics. At a glance inside, the jump seats, heater box, seat belt buckles etc. lack of headliner and the fact that the owner is flipping quick makes me suspicious not to mention what Jim...
I assume you were changing the rear main seal and not the bearing. The questions I have are, if you have been driving it you should have a feel for how it runs, how much oil consumption there is (or smoke) and if you have any excessive noises coming from the engine. With a proper valve...
It is my understanding that the F blocks used a bypass filtering system lending the top end to minimal oiling. The 74 block went to full filtration system which provided improved oiling throughout the engine. with a different feed to the head. Is the crack in the 74 block external or do you...
I agree with lcwizard but would like to add a couple of thoughts. You might want to consider what areas of the frame show after reassembly and weld in some new metal as much for appearance as strength. The other thing that caught my eye is even a good sandblaster cannot get all the rust ...