I slightly looked into this awhile back because I have kids. One thing I found is that there was a retrofit kit or something available to put shoulder belts in. I can't remember where I read that. Maybe an old TSB or something. But, I doubt you will ever find one of these kits available. The second thing I found was that, at least in NC, seat belt rules only apply if you have seat belts in your car. [DISCLAIMER: This doesn't mean you can take them out and have them not apply.] So, for kids, this means that they should sit in a seat with a seatbelt. If there is no seat belt, they sit where they can. So, even though kids are supposed to sit in the back, this means that one should sit in the front and use that shoulder belt. If there other kids, they can sit in the back with the lap belt. I'm not sure if riding in the cargo area in the wagons like we used to do in the old days is still OK or not, but I am pretty confident about what I just said about seat belts, at least in NC. Go to your state's DMV site for the facts.