What part of the pull tabs are you missing and are you talking about the knobs on the rear seat backs or the strap/ring on the rear seat bottoms?
Pics?
Regardless your best bet is probably going to be a yard or a part out here. If you are talking about the knobs on the seat back I believe I saw someone selling them on Ebay. If you are missing the strap part of the seat bottoms just tie some nylon in there and make sure the knot portion is down by the release mechanism.