Matching a bellhousing to my transmission

[usnabill]

Hello,

I have a 4.1L 250 in my C10 and a newly rebuilt Saginaw 3 speed. My current bellhousing won't fit the ring on the transmission (bellhousing opening is too small). I am having trouble figuring out what bellhousing I need to complete this project. I have the smaller 10 inch clutch installed right now, but all the bellhousings on ebay with the large opening are for 4 speeds. What gives?

[par4tom]

Do you have a pic? Sounds like the retainer is too large?

[usnabill]

The retainer is definitely too large. Do truck transmissions use a larger retainer than car transmissions? I may have a bellhousing intended for a car.

[par4tom]

I couldn't answer that for sure...but I just did an NP440 swap and took the bearing retainer to the machine shop and they machined it down to fit the 4 11/16 opening in my bellhousing.

I would guess your bearing retainer is probably just over 5 inches. Pretty easy fix...look up Music Man's threads...he know a lot about these and has some really cool photos of before and after.

[Captainfab]

The bellhousingf '67 and earlier had the 4-13/16" center bore. The bellhousings '68 and later had the 5-1/8" center bore. It sounds like you have a '68 and later 3 speed Saginaw. All you need is a '68 and later truck bellhousing with a 5-1/8" center bore. It does not matter if the original trans bolted to the bellhousing was a SM420 4 speed....the bolt pattern is the same as your Saginaw 3 speed.