View Full Version : Are M38A1 and M37 double-pulley generators the same?

04-23-2008, 19:56
I just came across some parts that I bought several years ago for an M37 that I once owned and wanted to find out if some of these parts are interchangeable with the military jeep. Along with the generator I have three voltage regulators too. I'll post photos of each. My plans are to eventually obtain another 1952 M38 military jeep so if the parts will work for the jeep, I'll hang onto them for a while. Thanks for any assistance with this inquiry. I could not believe how heavy the generator was!

04-24-2008, 09:25
Good question. I have wondered the same thing my self.

04-24-2008, 09:31
I had a couple of those generators last year, they were in rebuildable condition, but didn't sell at Aberdeen. I gave them away for free to another gent who sold them. Anyways, you're right, they are VERY heavy. You'd swear picking them up that it was a solid block of steel.

04-24-2008, 10:05
I suspect the they will interchange! For instance, the regulator failed on my M-37. At least it quite charging. I suspected the regulator. I didn't have one that looked operable. But I did have one straight off an M-211. It looked different, but had the same cable pin configuration as the M-37.
I installed it and it worked - is still working.

My bet is the the double pulley generator will work too, with the appropriate pulley. It says its 25 amp, like all the rest of them.

Lee in Alaska

04-24-2008, 10:19
Thanks for the replies! I did have a 1952 M38 military jeep during the 70's - bought it for $500.00 back then and it even had the arctic hardtop with it too! I pulled all of the military drivetrain stuff out and installed a Ford 289 in place of the 4-banger plus converted everything to 12 volts. I don't remember what I did with the generator or voltage regulator - probably went into the trash! Now that I am into military vehicles, I tend to collect parts such as this to use for projects and possibilities (like getting another 1952 M-38 for instace).

04-24-2008, 10:37
I believe the M38's had a double pulley generator and most were 60 amp..Maybe they had a 100 amp system on the radio jeeps? The double pulley set up on a M37 is for the 100 amp radio set up. It has a bigger regulator and usually a rectifier mounted out in front of the radiator. If you had this double pulley set up on a M37/M42 I dont see why you couldnt use the 60 amp generator with a standard regulator, 3 prong connector cable and just use the double pulley set up. The double pulley setup on a M37 was very hard on the old style flathead water pumps though.

04-24-2008, 10:39
After taking a look at yours I see its all 25 Amp.. Must be jeep stuff?

04-24-2008, 10:46
For the size and weight of these things you would think they would put out over 100 amps! I got very little information about the parts that I bought separate from the M-37 except that the former owner started accumulating parts to keep his truck on the road - then the divorce took place and I wound up buying the truck and the parts. I would have kept the M-37 except there was no title and it was too hard to steer and start. The winch worked perfect though!

04-24-2008, 11:00
I have a M38 and thats the generator that fits it. That generator will fit a M38. M38A1, M37 and early M151 and M151A1 as well as others. The regulators will fit also as long as they are the 25 amp one. The solid state regulator replaced the mechanical ones usually on the later vehicles such as the M151. If you are contemplating buying a M38 I would keep it


04-24-2008, 11:08
Thanks Fred, definitely wanting another M38! I still have the tech manual for the M-38 that I got when I worked at Patrick AFB back in the mid-70's; went over to Forms & Publications and acquired it myself while working at Patrick AFB Hospital. Testing these parts will be my next issue but I can come up with a way to do that with all the junk I have around here. I really appreciate the info!

04-26-2008, 18:46
All M series electrical parts are interchangeable, switches, lights, even generators and regulators. On the regulators that flat type you have pictured above is a late transistorized type, and if used you must change your amp gauge to a volt gauge (bat-gen indicator)and the spider harness for the gauges from 4 to 5 wire. The generators were all 25 amp rated, alternators ,which came along in 1966, (as did transistorized radio sets) were all rated at 60 amps and utilized an internal regulator.The generator an the alternator have the same mounting and can be switched for each other w/ some minor wiring changes. Of course all along the 100 amp chaging system was avialable for installation into a vehicle that required extra power such as a radio shelter truck etc. All the gen's an alt's used the same shaft size so that different pulleys could be exchanged between.