The NV4500 has a different bellhousing interface than an sm420. I use a 94-97 dodge version when I do the conversion because the dodge version has a pilot shaft that is 1 inch longer. The early dodge 2wd versions have a mechanical gear on the tailshaft of the transmission that drives a pulse generator. this could be easily swapped out to a speedo pinion for a mechanical speedometer. On a 4wd, the speedo pinion is on the transfer case, so that last fact is not so important. I then use an adapter plate from Advance adapter to go between the transmission and the bellhousing. I got the heavy duty dodge diesel version with the 10 spline 1.25 inch pilot shaft. I ordered a new 10 spline 1 1/8 pilot and a new bearing retainer which I spun down on a lathe to match the diameter of the chevy bearing retainer. Long story short... I use the stock clutch disc, pressure plate and throwout bearing for my truck. I have to use or make a custom pilot bushing because the tip of the transmission is bigger than a typical chevy transmission.
The NV4500 is longer than the sm420, and the shifter is about 5 inches further back.
