[quote author=Bobsbash link=board=1;threadid=6361;start=msg51318#msg51318 date=1066257450]
I'm trying to figure out what size bolt and thread are on the bottom of the sm420 that hold it to the bellhousing. Any help is appreciated. Bob
[/quote]
This is a .50 diameter bolt-13 threads per inch, about 1.5" or 1.75" in length. Remember, this is an American transmission, so any holes on the tranny should be ASE, and the fasteners should be ASE. The top bolts that thread into the Toyota three speed bellhousing through the mounting ears on the transmission are 18mm diameter x 1.5mm threads per inch, about 35 or 40 mm in length, assuming that this is going in behind a Toyota engine.
What engine are you running?