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Our M37 has a 100 amp generator and the cables go to a large heat sink mounted behind the grill in front of the radiator.
Can anyone tell me what the purpose of this is? Is this a standard thing for the large generator? Do we need to keep it on the truck?

Thanks

That is your Rectifier that converts the AC current to DC before going to you regulator. The 100 amp charging system is for supplying enough charge to operate additional load requirements like field communication radios etc. Your wiring harness is different than the standard 25 amp. You cant remove the rectifier without a new harness, and converting back to the standard generator.

What you have is a 100 amp alternator, not a generator. There would be no need for a rectifier if it was a generator because it would already be DC. Like DCook stated they are mounted in the M37 for field radio equipment and also in the M54 ambulances - if I remember correctly. So chances are your truck was a communications truck at one time. It may have had a comm shelter in the back or had the radios mounted to the troop seats, either way look for antenna mounting positions on the sides of the box.

I would keep it in the truck as they are pretty much maintenance free and they really charge the you-know-what out of the batteries, at least the one in my truck does. They also run additional belts instead of just the single belt on a normal M37. Make sure they aren't overly tight or you'll tear up the bushing in the water pump. If you do notice issues with the water pump change it out to a modern sealed bearing pump, Midwest Military carries them. They are more forgiving than the stock bushing pump but you still have to be mindful of how tight the belts are.

Is your battery box still intact? Mine was removed and had two massive 12 volt truck batteries stuffed into the compartment under the seat. The batteries are supported and locked in place by wood blocks, cut to fit. I'm assuming they did this to get more run time off the batteries while operating the comm equipment as my truck was a radio truck in its past life.

Dcook, I thought standard was 55 amp? no?

to my limited knowledge there were two charging systems, a 25 amp generator, and the 100 amp alternator. My truck has the later, and it is really huge, heavy 4 belt beast, If you have the alternator, be sure to wear steel toe boots when carrying it around. HC