You need an adapter plate between the bellhousing and transmission like this one.
http://www.amazon.com/Advance-Adapters-712550-Bellhousing-Adapter/dp/B000FPZTP6This adapter will require extra machining to fit a 1948-1967 chevy or gmc truck. The indexing lip on the adapter plate needs to be cut down from 5.125 inches to 4.686 inches, or the bore in the bellhousing needs to be opened up from 4.686 inches to 5.125 inches.
The 1994-1997 Dodge 2wd NV4500 is the easiest to swap. This version can easily be converted to a mechanical speedometer. There is a heavy duty diesel version, and a lighter duty gas version. Idealy you would want the gas version with the 10 spline 1 1/8 pilot shaft. If you get the diesel version, you can swap out the 10 spline 1 1/4 pilot shaft for a 1 1/8 shaft without getting insde the transmission. You will also have to swap out bearing retainers.
There is a crossover throwout bearing that will work on the larger NV4500 bearing retainer. The bearing retainer can be turned down on a lathe, and the stock gm throwout bearing can be used.
The Dodge NV4500 has a pilot tip of 0.750 inches. The stock pilot tip of most gm transmissions is 0.590 inches. This means a non stock pilot bearing/bushing needs to be used with this transmission.
RECAP:
Dodge 2wd NV4500 from 1994-1997
With a little machining all stock clutch components can be reused except the pilot bearing.
The transmission can easily be adapted to a mechanical speedometer. (later versions and the gm versions relied on a velocity sensor.)
Below are sites of interest
http://www.high-impact.net/transmission_and_gear/nv4500.htmhttp://www.novak-adapt.com/knowledge/nv4500.htm
