64 Dart driveline

The boot/clamp kit you need for your '64 is Q-102 (same as '60-'62 Valiant/Lancer). Sounds like you got the smaller Q-101 which is for cars pre-1957.

Bernbaum doesn't officially support cars newer than '62, so that's where his catalogue stops. Many parts that fit '62s also fit '64s.