Switching my sm465 to a nv4500 in a 1969 Chevy C20

[raycow]

Your question is a good one. My personal feeling is that the cast iron bellhousing is way overdesigned for the job it has to do. We have a member on one of the boards here who is planning to hang a Gear Vendors overdrive off the back of his stock 4 speed without any additional support.

If you intend to use the truck primarily on pavement, I can't see how you would have any problems with the stock mounting setup. If you will be driving on badly rutted roads or off-road, then maybe you might want an additional crossmember under the rear of the NV4500 just for insurance.

Ray