All of the Toyota bellhousings I've seen have ribs running from front to back on the outside surface. I assume that this is a strengthening measure. I have a factory 7MGTE bellhousing that I was saving to use as a donor for a welded hybrid 4x4 project. I'm going to look at it tomorrow and see if i can come up with some more questions for you. -- Matt

'89 4runner SR5, 3.0, auto (fun)
'93 xtra cab, dlx,3.0, 5spd (work truck)