360 engine vibration

FWIW..... TC's without drain plugs can be drained by drilling a small hole in the outer edge and then a very short sealing screw installed. The drill has to be set up so as to not penetrate the housing more than a few thousandths of an inch, to avoid getting into the innards. I've never done it over concerns for metal in the drilling, but numerous trans shops did this for years as a regular practice. YMMV