Now the block heater's out....
 

Have an '87 F-250 with an '88 7.3 IDI in it that's been having starting problems. Mechanics have been unable to locate a fuel heater on this truck, but it's having the usual fuel heater o ring problems; needs block heater in warm weather, hard to start, crap in fuel filter....

And now, the block heater's crapped out. When I get a new freeze plug type heater what size do I need, and how many watts? (I might be headed to North Dakota in a couple days)

Before you pull and replace the heater make sure it isn't just a bad power cord to it. A broken wire in the cord will keep the heater from working and it is a common problem.

That was my first thought; used a test light, and the element's done.