This is a follow up on my efforts to have my differential repaired in my 55 76R roadmaster. I needed a replacement ring gear carrier. I have heard that early 55's have the ring gear riveted to the carrier, latter ones are bolted. I obtained a ring gear & carrier fron Msgr. Douglas Cook in our local BCA chapter, it was out of a 54 Century (series 60) and was riveted, but in great condition. Not knowing if thie unit would fit in my Roadmaster (series 70), I took the Roadmaster & the 54 ring & carrier to a top notch differential shop. to make a long story short, the next day, they called and said the Roadmaster & the Century carriers were exactly the same, even had the same casting #'s on them. They removed the Century ring gear, by machining out the rivets and installed my Roadmaster ring gear using my bolts. They needed to reface the ring gear a little because the bolt heads were a bit larger in dia. than the rivets. They needed NO other parts than what I had brought, and the total bill was only $300.00. I am pretty sure that all ring gear carriers are the same for 40,50,60 &70 series cars, at least on 54 & 55 cars, the ring gears could be a different ratio of course. SHE RUNS GREAR!!! Larry Minery