I've seen plenty of 1st gen cars with the front seats replaced with 4th gen seats. However, has any one ever replaced the back seats ? More specifically, has anyone added the updated rear seat three point seat belt system to a 1st gen car ? My kids are into booster seats, so their seats don't work in my 69' anymore. My LT1 is fine, since it has the lap and shoulder restraints. Any ideas, suggestions, comments