Hey all,
Thanks for the input. I looked at the Mar-K website, which is here:
http://www.mar-k.com/tailgate_closure.html ...but they don't make the system for mid-60's trucks. That's the kind of thing I'm looking for. I may need to fabricate it from steel stock, eh?
Personally, I think the seat-belt solution looks pretty cheezy.
---Scoob