For the NV4500 trans you'll need the bellhousing too ,probably with the hydraulic clutch set up the 4500 uses.So long as it's a GM 4500 from the old design small block the housing SHOULD bolt up but check out the starter nose hole in the housing for fit.And the 4500 electric speedo drive may require some reworking, and 4500's are usually quite costly.Avoid the Getrag 5 spd used in full sized trucks from 88-92 or so,not the best.The 3500 NV OD trans from a 91 and up 4.3 S10 will bolt up the the small block,has a 300 lbs ft torque rating, should be ok.But again,the 3500 has an intergal clutch housing, you'll have to deal with the hydraulic clutch and speedo interface. Also check out the NP883(M6Y code) 4 spd od found in early 80's GM trucks, I run one in a 51, and Richard here has one behind a 292 I think.Some have a GM bolt pattern, some have a funky Mopar bolt pattern, but it has a 10 spline input shaft like your truck ,it's the same length as a Saginaw, 21 inches, and uses the Saginaw or TH350 output spline, so it should be a bolt in.
