What kind of vehicle are we talking about. Some cars the hard 1-2 shift is considered normal (By the factory. Not backyard mechanics...). Also, are you positive it's your tranny shaking above 70? Sounds like a wheel balance issue to me.
1999 Chevrolet Camaro SS (PC'd)
1994 Chevrolet Beretta Z26 Q4 (W41 M90'd)
2004 Chevrolet Silverado 2500 (4WD)
My wife's cars:
1971 Dodge Charger SE (stock and original 383 auto)
2004 Subaru Impreza WRX (kid-hauler)