The TH 350 member is flat and looks like two peaces of metal spot welded together. The 400 member is round tublar. I have the part # at the shop but not here. The new one don't cost but around $60.00 from G.M. Let me know if you need the part #.
Didn't only the big blocks come with a TH400? Wouldn't the trans mount pad be offset to the passenger side in that case? Is there enough room on the pad to re-drill the holes if a guy has a small block and wants to put in a TH400 (where the small block engine is centered in the car instead of being offset like a big block?
All Camaros (and other GM cars) had the drive train offset 1/2 inch from center. The centerline of the crankshaft, transmission main shaft and pinion are 1 inch closer to the passenger's side of the car.
'69 RS/SS396 pro street
High Performance Drive Train Parts And Service www.lubedealer.com/biggearhead