I know next to nothing about the Doug Nash "Crash Box", but I assume that it is similar to the clutchless transmissions used in some classes, and they pop out of gear under compression unless you hold the stick in gear.
1964 tube chassis GTO, 2750#, 606 cu. in. Indian Adventures tall deck w/Super Chiefs
best 1/4 et. so far; 8.2550 @ 164.17 all motor