I have a 1998 Cherokee Sport with a low back (fold-down) rear bench seat. Ideally I just need head rests, but that's probably not an option.

Is there a way to put a Grand Cherokee bench seat in it or install bucket seats to protect passengers during a rear impact crash?

ive seen internal roll cage kits that have an option for a rear head rest. but if youre not looking for a internal roll cage then its kinda pointless

I have a 1998 Cherokee Sport with a low back (fold-down) rear bench seat. Ideally I just need head rests, but that's probably not an option.

Is there a way to put a Grand Cherokee bench seat in it or install bucket seats to protect passengers during a rear impact crash?

Try having an upholstry shop install the removable type head rests on them. For example, the ones in back for the Mazda Tribute come off. The ones used some early XJs in the front also come off.