i have installed block heaters probably about 10 times. i always buy what i consider to be the proper tools.snap on for best precision craftsman for 1/2" drive. my 19mm allen is 1/2" drive snapon and the socket {forget size} is craftsman.i must not have installed one on a 300sd in the car because i do not remember removing manifolds.i only remember removing starter when in car.when doing an engine swap i always put in block heater. a local shop i know uses a lift and a 6' cheater bar. i have never had a lift but i love cheater bars.