so i just brought my first old mopar. introduced myself in the welcome wagon.. i have been going over my new car trying to learn a few things about it. i have some charts that help you tell what rear end may be in your car. i just purchased a 1965 dart gt. appears to have been a 273 car. have noticed a few changes to it including rear spring hangers. i look at the left side of the diff and i see a big 9. seems to me this is a 489 center section. when i measure the bolt pattern on the wheels i find it to be 5x4 the small bolt pattern. can you installed a 489 center section in a old housing? where would i find the casting numbers on the housing to help identify it.