Skaterock,
Sorry for taking so long to get back to you, had a dead computer hard drive to deal with.

The controller does not need to be replaced to run the manual switch.

The manual version other than it is a pain to remember to do for a while is actually better because there are a lot of times you do not need to cycle the glow plugs. Since they are manually controlled they do not cycle when un- needed. This saves them for when you do need them.

Like you go in a store for 20 minutes and when you come out to start the truck and the glow plugs cycle. You should not have to cycle the glow plugs 20 minutes after running the truck. At 10 degrees outside I can normally start mine by just turning the key, no glow plugs, for 3 or 4 hours after the truck was up to temp. If it sits all day, then I cycle the plugs and away we go. When it is plugged in I never use the plugs. Each time I do not cycle the plugs I figure I just bought 1 more day of them working. Make several short trips in a day and the next thing you know your plugs will last months longer.

The other style (square box) of controller was on the 87 6.9 and the later 7.3's.

Most places will be asking around $120 for the old style controller