I think the part you are referring to is what is called the clevis. Shosource has a repair kit that includes new parts that improve on the stock design. It can be found here.
https://shosource.com/products?olsPage=products%2Frod-shifter-clevis-repair-kit
Welcome. Hope to see pics of the car at some point.
There is a vast array of info here that should help with whatever your plans are.
Shosource is down temporarily. They posted on their Facebook page they were having server issues or something but can be contacted directly through email for...
Oil pressure sending units use pipe threads meaning the threaded area is tapered. The design causes it to tighten before it is threaded all the way in and seals the threads as it is tightened.
It’s not designed to thread all the way in.
The first gens have two “subwoofers” that are held underneath the primary speakers in the rear package tray. They are held in by a rubber strap from underneath in the trunk so there is no adapter required as long as the strap fits over the magnet of the new driver.
Most fill plugs like these are pipe thread which is tapered so that as you tighten it it gets tighter in the hole causing a compression seal.
Not positive but based on your dimensions it looks to be a 1/2 in pipe plug to me. :shrug:
Any regular ol hardware store should have one in stock to...
If you’re planning to machine your crank I have some bearings that are .25 and .5 oversized if you want them. You won’t find standard size unless you’re planning to spend big $$$.