I have a 1954 Bel Air with a 2nd design 3 speed. I rebuilt it with all NOS parts, including a new synchro drum and cones. It shifts up through the gears perfectly. When I try to downshift from 3 to 2, it grinds. I've tried double clutching and it just won't go into 2nd from 3 unless I'm almost stopped. I've measured and triple checked everything and it all seems to be working. The cones rotate in the synchros, the gears all turn and work properly. I've even tried shimming the energizing spring. I have 2 questions..1. What can cause it not to downshift when it upshifts perfectly? 2. Does the 2nd gear thrust washer have any other function besides as a washer between the bearing and 2nd gear? I am using 90w tractor gear oil with no synthetics...thanks for any help!