Hi there! We just got a 78 Buick park Avenue Electra and I want to take my five year old in a booster seat and our 3 month in a rear facing infant seat for a drive. Do I need to install shoulder belts in the back seat or am I ok with just lap belts?? TIA
Hello!
First, I wouldn't drive anyone with the original lap belts. They are likely well past their prime. They should likely be replaced.
It's fine to install a rear facing seat with a lap-only belt, as long as the belts lock (likely at the latch plate, by pulling the tail tight and having the buckle lay flat parallel to the belt. If not, it must not spool out any more once buckled and tightened- automatic locking retractors.)
If your 5 year old is in a belt positioning booster, you would need to install 3 point lap-shoulder belts (whether this is possible depends on if there's an appropriate spot to anchor them.) Alternatively, if the front seat has shoulder belts and you can't properly install shoulder belts in back, you might choose to move it all the way back and put a booster in front.
If your child is in a combination seat (forward facing with a harness and later becomes a belt positioning booster) you can install with a lap belt, again assuming it locks. However, an important safety feature is a tether anchor. Parts to retrofit them in Buicks are no longer available from the manufacturer. You could look into an aftermarket retrofit, if you chose to.
Overall, I would recommend not using this vehicle for long drives or at high speeds even if you find a way to properly restrain the children. For parade type driving or low speed cruising nights, it may be doable, but vehicles this old lack many modern features that are very important in crash safety, so limit time in it.