Transmissions intended for use in cars as original equipment don't have threads in the bottom mounting ears- - - -passenger car bellhousings have threads in all the holes and the bolts go in from the rear. You'll need to use bolts and nuts on the bottom. Try 1/2-13 grade 5 or grade 8 bolts.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!