I am glad to see that the synchro rings are available again. The complete synchro drums are getting very hard to find and are very expensive. 50 years ago rebuilding the synchro drums with new rings was common. 1953 was a transition year that GM made some improvements and there was an early 53 and a late 53. The quick way to tell the difference is the early one has two lugs on the synchronizer and the later one has four. There are also some changes to the gears and one of the bearings. Other than the synchros, almost all the rest of the parts appear on eBay quite regularly.