i have an 81 monte with a 229 3.8 with a TH250,swapping the 3.8 to a gm perf. 350 crate with head work, thumpr cam, roller rockers, edelbrock performer rpm intake, 670 street avenger, and i just had a h.d. TH400 out of a 1 ton pick up rebuilt, roller sprag, red clutches, tci reverse manual valve...