I was driving my 1963 C-10 today and got it up to 3rd gear for the first time. I noticed whenever I try to downshift between 2nd and 1st the gears grind if I try to move the lever out of neutral. The only way to downshift into 1st is to bring the truck to a complete stop. It does not do this between 3rd and 2nd. I've tried double clutching, but that didn't help. What could be causing this? My transmission is the standard 3-speed column shift.
