I had a 68 MX8 and the only difference I saw was a little extra metal on the action where the cocking lever on the forend inserted. Had to be careful not to break off the way thin metal on the action. I saw no diff in forend iron or hanger but that did not include measurements just visual.
Lippard says T1's ended in 1968 w/ #33250. Unless someone has seen a T1 w/ a higher # that would probably be a good # to work w/.