This Top Dead Center (TDC) tool makes locating top dead center on your 500/650/750 c.c. Triumph (and 69-72 BSA A50 or A65) very simple, very useful for installing your points, electronic ignition, or Joe Hunt or Morris magneto. Our TDC tool has two sets of threads allowing for proper use on all year ranges of with only one tool! This specialty tool threads into the hole located on the crankcase right behind the cylinders, and when you apply light pressure to the plunger while rotating the motor, it will drop the plunger into a slot on your crank which marks TDC. This tool is for early Triumphs 1963 up to and including 1968, as well as late unit motors 1968 and up. Just flip the base around so the threads are correct for your motor! This tool also works with BSA A50 and A65 unit twins such as Royal Star, Lightning, Thunderbolt and Firebird Scrambler from 1969-1972. Replacement for OEM # 60-0571, 60-0572, D571, 61-7022, 60-2195, 60-1859, D1859, D2195, D7022