My 79' 300SD doesnt have a block heater. How hard is it to install??

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Mark

1979 300SD southern survivor (Old Yeller) 151K
1967 Cougar XR7 CA car (Precious) 88K
1967 Pontiac LeMans TX car (08' resto project) 72K
1995 F350 Powerstroke Dually from TX 139K
1996 Honda Accord (the winter beater) 134K
1994 Fleetwood Wilderness 30' fifth wheel