Anybody running a Gear Vendors?

[69GMCLonghorn]

I have a '69 GMC with an NP435 4-speed. I ordered a Gear Vendors unit thinking I had an SM465. When I realized the problem, I called them and they were unable to provide me with the correct adaptor and I sent the unit back... very disappointing. They had an adaptor for an NP435 in a F**D, but had no record of that tranny ever being in a GM truck. I even E-mailed them some pics of the tranny. No dice.

What I'm trying to figure out is if I was just dealing with a mental MIDGET, or is there really that much of a difference in the tail ends of a GM and a Ford version of the NP435. Anybody have any info on this? I'd still like to do this someday if I could get them to find the right adaptor.