I am replacing a 270 in a GMC DUKW. One of the options I'm considering is a later GM 6-cyl, either a 250 or a 292. I'm hoping to find a bell-housing that will connect the 250/292 (small block Chevy bolt pattern) to the existing Clark 204 transmission.
First try: The stock cast iron bell housing for the 250: It's the same length as the 270 housing and making an adaptor ring for the centre hole is no problem, but the 250 housing doesn't extend far enough down. There's no metal where I'd have to drill for the Clark mounting bolts.
Second try: There was an old Chevy school bus behind my barn. The small-block had been pulled years ago, but the bell-housing was still attached to the transmission. It seems to have 2 sets of bolt holes on the back. Neither of them is what I need, but there's plenty of metal to drill another set. Problem is, when I examined the engine end, it's not a small-block pattern. It looks like one, but slightly bigger. Did some of the small-blocks use an adaptor plate to mount a larger bell-housing? Anyway, it won't fit.
Are there any other possibilities that I might find in my local junk yard, or is a custom bell-housing the only solution? If it is, then some of the other options start to look attractive.
