Pete, many years ago I changed the tranny on my 38 pickup, I found a newer tranny with synchros that was a for a three on the tree shifter, the case looked the same. I took the lid off and apart and found that the shifter forks (on the newer trans) would interchange with the original floor shifter forks, the shifter forks were different in both trans. I took both lids apart and put the forks from the newer tranny on the old floor shifter lid and it worked. The forks are riveted in place to the lid, remove the rivets switch the forks and reassemble, it was a long time ago and I can't tell you what year the newer trans was, more options