You guys might be in luck. I don't know if this will help you with your '64, Brent and I don't know what kinda truck you have, M, but Deve Krehbiel has recently posted a very fine installation how-to on his website for an Advance Design cab.

Advance Design 3-Point Seat Belt Installation


Larry Kephart
1937 Chevy Utility Express (Deerslayer)
1955 1st 3100 Chevy (BillyBob)
2017 Cadillac ATS-V (Elvira)
Boca Raton, Florida
e-mail: [email protected]

http://www.laroke.com/larryk4674/1998/billybob.htm