Any crank triggers I've installed are a snap to install. I assume you're talking about race/aftermarket setups like MSD, Mallory .........may have to shim brackets to center the pickup on the trigger wheel, and same with pulleys for alternator and such if you run them. The trigger wheel mounts directly to the balancer and moves pulleys forward 1/4". You'll have to lock out the advance in the distributor and phase the rotor after setting timing. Timing is adjusted by moving the pickup, not the distributor, but it's easy.......and timing is rock solid once it's set!