Nick,

I used Amsafe airbag seat belts in the front and three point automotive style belts in the rear.  However, the rear belts would easily work in the front.  I got the belts from seatbeltpros.com.  For the backs, I ordered 13 inch cable buckle, standard door post fitting, 110 inch, black, no hardware kit.  $160 shipped for the pair.

Pete