Some parts are very hard to find on some of the older transmissions. Here are some examples from my three-speed circa 1946. Finding a 2nd and 3rd gear synchronizer drum will cost about $400-500 due to how rare that item has become. There are synchro rings that can be replaced instead of the whole assembly but they are almost extinct. I needed an input shaft and that was very difficult to find and expensive. Thanks goodness for the internet. Ultimately I was able to find the parts I needed and the transmission should last another 100,000 miles but doing most of the work myself will result in a $550 rebuild. As 801curt said, I would just put the trans you have in and hope for the best.
