I got the 3 point seat belts from Rick's Pickup Parts in Mesa, AZ 877-641-1387 and website
www.****************.com
I had to make the "L" bracket and get the bolts locally, Installation was straight forward and pretty easy, I did not want to drill any holes, so I used exsisting hole for the "L" bracket. I removed the seat and also used exsisting mounting holes and shoulder bolt for the other side of the seat belts. I might come up with a different "L" Bracket so I can turn it 90 degrees like in the pic at Julianos below.
there are installation pics at:
http://www.julianos.com/how2_67chevy_truck.html
see ya!!!
Jeff Smith
Pensacola, FL