1957-1964 Borg Warner Early T10 4 Speed Transmission input shaft, new old stock reproduction gear, wide ratio 2.56:1 1st gear with 25T, high quality part originally commissioned by Bob Bartlett of 4 Gear Trans Co, this works with aluminum and cast iron cases that utilize a C clip to retain the front bearing and not the 1963 style case requiring a nut, thanks for looking and please check out the other items in our ebay store.