I forgot to mention, your car is a 198 slant six car, and yes they did obviously make them in 1973.
Personally, i would sell it unless you are very attached to it.
Holding on to it because it's rare doesn't apply in this case.
Actually, it's a cool car because it was so plainly optioned, i bet the rallye wheels were added. All rallye wheel cars in '73 were big bolt pattern, and your car would have had the small bolt pattern seeing that it had manual brakes. If it had power brakes, you got the bbp front disc brakes automatically and a bbp rear end. They did not install sbp rallye wheels on cars after the '72 model year from the factory.
Just my opinion for what it's worth, i hope it helps you in your decision.......
