modern receiver hitch and M37

[Doc Dave]

I have a '52 M37. Now that I have finally finished my civvie PW resto, I am going to start on the M37 this winter.
My M37 is going to look stock on the outside but have some upgrades in the power train, seats and brakes.
Last month I removed a stock class 3 receiver hitch from my 2001 Ram and replaced it with a class 5. I thought this old hitch would be just extra iron laying around unless I could sell it locally.
Last week I was doing a little measuring and inspecting, and just for curiosity sake took the receiver hitch over and held it up to the frame rails of the M37. It looks like it will drop right in with just a very small amount of grinding of the edge of its ears in a few places! The receiver opening will be below the pintle, so I can keep that. How often does that happen- with this many years and design differences? Maybe Murphy is not always on duty!

[jrodjared]

Wow great! Any pics of the install? Does the stock hitch have the tabs face outward or inward? I mean does the hitch mount in-between the frame rails or on the outside?

[Doc Dave]

Hi Jared,
I will try to get some pics soon...I got the frame and axles done but then the project has been on hold and I haven't finished the hitch.

[John Mc]

Doc Dave - I'm wondering what ever came of this project. I'm just getting started on my M37, and trying to figure out how I might add a receiver hitch.

[Doc Dave]

After my original post in 2011, I had a lot of "life happens" situations going on. I only recently went back to the M37.

Among other things I got the gas tank Renu'd and installed, and fabricated the fuel and return line fittings to this.

I'm happy to say the stock Dodge 3/4 ton pickup receiver hitch from my 2001 Ram fit the M37 perfectly!
i was able to use the existing holes in the hitch flange as a guide to drill 1/2" holes in the lower frame ears. I used grade 8 bolts to attach the frame and the results are very nice.
i did not have to grind or modify anything.

I blasted the hitch in my media blaster cabinet and then painted it black.

[John Mc]

Doc Dave - still hoping to see some pictures of your installation sometime.

I've got to make the decision on what I'm going to do with my installation. I misread your original description, and thought you had mounted the hitch on the rear cross-member. Mounting to the frame seems like a better way to go, and being a bolt-on installation makes for easy removal if I need to do gas-tank work in the future.

Some photos I'd love to see:

• Where the receiver ended up in relation to your bumper (height below your rear cross-member and/or pintle hitch, as well as how far the receiver sticks out behind the rear cross-member.)
• Underside of the truck showing mounting to the frame
• I'm especially interested in where the bolt holes from the hitch fell on your frame. In talking to etrailer, they say that the distance between frame rails is standard among most full-size trucks. What differs is where the bolt holes are and how much "drop" they build in from the frame on the truck to the hitch's cross bar in order to get the receiver to come out under a modern truck's bumper. It appears that I only need minimal drop to clear things on the M37, so there might be other options that out make for a tighter fit than the stock 2001 Dodge hitch fit.
• Anything else you think would be helpful as I try to make my decision. I'm considering buying a new aftermarket hitch for a Dodge full-size pickup, so anything you can show me where I might need to be concerned about the fit as I consider the various aftermarket models would be appreciated

I'm also interested in your comments on how it has been working out for you. What kind of loads have you towed, and have you had any issues with your installation?

I've found some really good options for powering 12V trailer lights and 12V trailer brakes for my M37, so the only thing remaining is to figure out the mechanical installation.

[Doc Dave]

After my original post in 2011, I had a lot of "life happens" situations going on. I only recently went back to the M37.

Among other things I got the gas tank Renu'd and installed, and fabricated the fuel and return line fittings to this.

I'm happy to say the stock Dodge 3/4 ton pickup receiver hitch from my 2001 Ram fit the M37 perfectly!
i was able to use the existing holes in the hitch flange as a guide to drill 1/2" holes in the lower frame ears. I used grade 8 bolts to attach the frame and the results are very nice.
i did not have to grind or modify anything.

I blasted the hitch in my media blaster cabinet and then painted it black.

[Doc Dave]

Addendum/clarification to my post:
I forgot to say that for the rear-most bolt to attach the hitch to the frame flanges, I removed the stock rivets that attached the rear crossmember to the frame flanges and then put a 1/2" grade 8 bolt through that on each side.
To help drill the other holes in the frame, using the holes in the hitch flanges as a general guide, I used big C clamp- type vice grips to hold the hitch up to the frame ear so as to allow me to mark centers on the frame flanges with a center punch.
Then, I used a "poor mans magnetic drill" to make drilling up from under the vehicle much easier. I put a small towel around the rear handle of the 1/2" drill, and placed this in a vertical position under the truck frame; the handle fit in the saddle of a floor jack. Once aligned, I gradually pumped the handle and drilled the holes much easier! I learned this trick from a local mechanic.
The back surface of the receiver hitch, when looking at things from the side, is maybe 1/2-1" forward of where the end of the pintle is, if you put a plumb straightedge down from the end of the pintle.
The pictures that follows should help with understanding the fitment.

[Doc Dave]

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[Doc Dave]

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[Doc Dave]

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[Doc Dave]

3548D754-8220-4E08-BC2D-1CCAC52622F0.jpg

[Doc Dave]

86F55D56-726C-47D9-8F7D-4FF32FD9D0E4.jpg

[Doc Dave]

To answer one of your questions, I too thought that ideally the "drop" of the hitch would be somewhat less; the receiver would be only say 2" below the pintle. As it is, it's not "bad" unless you were doing rock crawling maybe.
If one could find a receiver hitch off the shelf that has a little less drop, then it might be perfect.

To fab different hitch flanges with less drop (and correct strength, etc) is above my pay grade!

[John Mc]

Thanks, Doc Dave . That is very helpful. I spoke with the folks at eTrailer about this, asking if they had something with less drop, as judging from the pictures of the aftermarket hitches sold by Curt and other manufacturers, the hitches to fit a 2001 Dodge Ram had more drop than I would like. I'm assuming this was needed to clear the bumper on the 2001 Ram. In my searches of their site, I noticed that the Curt 14001 which is sold to fit the 2001 Dodge Ram also fits Dodge full size pickups all the way back to 1967 (which is as far back as the dates were offered on the eTrailer site).

I asked if he had anything with less drop that would fit, and mentioned that I was mainly interested in the width (so it would align with the frame rails) and the drop. He said "just about every hitch we have for a full size truck will fit for the width, they are all the same. However the holes wont line up." (I had no idea that most/all modern full-sized trucks shared the same frame rail spacing.) When he learned that I would be drilling holes anyway, he said that I should understand they can't guarantee it structurally, but if I was going to drill anyway, just pick one with a drop I liked and that the holes didn't interfere with some other structure on the frame.

Unfortunately, eTrailer doesn't have drawings showing dimensions and hole locations, so it looks like I'll need to make a trip to a trailer hitch place in my area and see if they have anything that will give me the amount of drop with holes in acceptable locations. I'm hoping they have some varieties in stock that we can look at for fit.

I don't do rock crawling, but the approach and departure angles are still important to me. I do intend to use this truck in the woods, either by itself or hauling my log trailer with hydraulic loader. Most use will be on the access trails, but some of them can be rough in spots, mainly due to the installation of water bars and broad-based dips for erosion control.