Are you running any type of rear support bar in it?
My 73 (also type 1 powered) had a home-made rear support when I got it . . . not really for support, the guy who converted it put it in for an anti-torque bar. Anyway, a couple of engines back, I couldn't find a good used case with the type 2 mounting points, so I just used a type 1 and left the bar off. It's been off for about 3 years with no problems . . . so far anyway.