Jed,
When you say you are looking for a bell-housing, are you referring to the clutch housing or the cover for the u-joint. Most likely you want a clutch assembly bell housing.
Either way, post a Parts Wanted ad in the Swap Meet.
If you are looking for a 3-speed clutch housing, maybe someone will comment on GMC and Chev truck housings being the same. Also, the 3-speed housing has a shift-linkage post on it (that post is not on the 4-speed housing).
