When I removed my old TM my rear bracket was held on by a threaded stainless screw. You can see the large round black head of that screw in the last picture. The front bracket is slightly different with that T shaped opening. Mine had a locking pin that fit through that T shape and then turned 90 degrees so the T would not come back through it was held in that position with a tension spring. The spring was not going to work with the new set up so I had the locking pin re-drilled so that it fit super tight with out a spring (basically moved the cross portion high up the shaft of the pin). If I recall when we installed that one guy and to put all his weight on it to push down the locking pin, while another guy turned the pin with a wrench. It is solid! Lastly, I wish I would have leveled it more, mine is not too bad there is a slight angle to the TM shaft like you said but nothing major. Fishes Great
This was a major undertaking for me, like most I think, I have a family, house upkeep, kids playing sports to attend, life in general. Add to that you and I own old boats, it's not easy to get access underneath or find compatible parts. In order to fish how I want this was going to happen for me because the alternative of buying a newer model was not an option, the whole process took me about 2 months. 2 months I didn't fish but it paid off big time last summer and so far this year. Factor into that shipping of parts and fabrication of the plate and new locking pin. Again all well worth it and I am proud of MY upgrade, plus face it that old Motor Guide was/is garbage. Hope this helps