I was trying to find some more information about a good heavy duty swap. It looks like the NV3500 is out of the question because of the one peice tranny/bell. I really couldn't dig up much on the "zf" either. It looks like the best way to go would be the NV4500. I think there was someone here on the Stovebolt that put one in his truck. Said the one to use was out of a gas dodge due to a mechanical speedo, and a longer input shaft (so an adapter could be used). If anyone has any pictures of this swap, or knows of a source for adapter I would appreciate it. Advice on which gears to go with would be nice too. The only thing I'm worried about with this tranny is how far apart the gears are.
