Additional info I found.
In the interest of keeping all of this info in one place, I'd like to mention something I found last night in a post on SS from 2014. I don't think I can 'legally' cross-post so I'll paraphrase.
This is regarding the 2 bolts that attach the arm/mount to the transmission:
Replace the bolts with grade 8 studs, flat and lock washers. Use red loctite. The driver's side stud has to be shorter than the other.
The post is titled Transmission Support Mounts (to give credit to the original poster).
This is something I think I'll try since one of my bolts had fallen out and was jammed under the trans somehow, making the entire mount quite loose.
I hope I didn't break any rules by including this.
1968 M-715 w/1100R16s on Stockton wheels, H3 headlights, 2bbl upgrade...