Your car is perplexing to say the least.

I wrote sometime ago that I thought it was a bad starter. After reading your many posts, it appears to be the starter or lack of a ground directly to the engine block.

I was spending some time thinking about the transmission/flywheel. I wondered if it was possible to bolt it up wrong. I have to say that should be hard to do so, I am back to the starter because the flywheel would affect the clutch operation too.

A bad armature or solenoid can either suck a battery down because the power is either not used through the windings efficiently or not letting the juice get in to the starter motor. If the armature is bad, it will take out the solenoid because the current fries the contacts and it gets worse in to ways.

To properly rebuild a starter; all armatures need to be tested on a growler. If your old starter just quits it is a safer to rebuild it yourself than to buy a rebuild because you know what you have, if you tear it down. If it looks bad then you go shopping, with knowledge, for good parts from an auto electric parts house or the next best choice P&P. These starters have been around for years.

I do not trust rebuilders to be thorough. They gamble, with some idea, that most starters have bad engagement gears, worn brushes or a bearing in a worst-case core average. They fly through them with the least expensive labor and sell an insurance policy for back up. You know, limited and lifetime warranties are a business.

The starter appears to have all the problems no matter what you hook to it.
Phil