Wanting to replace the bolts for bolting the transmission onto the engine, what is in it now are whatever someone had on hand. Anyone know what size(s) and hardness I need and did they use lock washers?

hi

grade 5 with conical washers

I seem to recall captive lock washers on the bolts

Correct originally, don't forget about the two 7/16 bolts on the lower block going into the trans.case, one under the starter and the other on the passenger side down low also bolting into the tranny case

autos had sems style, not lock washer that was 4 speed.