I assume this will be going into the rear seat. If so get the child seats with the teather strap. It is designed to use a regular lap belt and then it has a strap built into it that goes over the back of the seat and fastens to a hook in the floor. All the new cars now have this attachment point built in by law but you could add one to the blazer real easy. Just make sure you use a plate or seatbelt washers under the floor for it to bolt thru. If your car seat was built in the last few years it should have this strap on it or have came with it, ask your wife were it is
Kevin
LFD Inc.