willysmjeeps.com

Hello, I have a few questions about the M-38. I have searched and found many answers to my questions, but still have some few simple ones. I am very familiar with the MB-GPW jeeps, but know nothing about the m-38's.
#1
How do you tell if the engine matches the jeep? Do the numbers match?
#2
Are the tires 700-16, or 600-16?
#3
I see regular slotted wheels in many pictures. Original?
#4
Axle ratios 5:38? Dana xx?
#5
(BEST FOR LAST!)
Is there anyone within 2 hours of Cincinnati that has one decently restored or somewhat original that I could go and take a look at?

No dumb questions, only dumb answers!
I may not know all the answers but this is what I've learned about my M38.
1. Engine numbers and body numbers do not match. By referencing databases of known original body and engine numbers you can see if what you have is close to what could have been together when the Jeep rolled off the assembly line but no records exist as to what engine was paired with what body. Replacements and rebuilds when they were in service mixed things up as well.
2. M38's were upgraded over the MB's with 7.00-16's
3. M38 wheels had slots, a safety ridge to help the tire stay on the bead and a 1/8" hole near the lug nuts. There has been some discussion about the hole and whether it designates a "military" wheel or not but my largely orginal M38 has them.
4. Front is Dana 25, Rear is Dana 44, production M38's were 5.38, some pre-production models had 4.88 axles.
5. I'm in N. IL, so out of your 2 hr. range but there may be others near by. If you are coming through my area, you are welcome to look at my Jeep. Not running yet but I hope it will be soon!
Resources: http://www.cj-3a.com/m38.htm http://www.cj3a.info/sibling/m38/pilot.html

I'm at your 2 hour mark, near chillicothe ohio.

Close enough Supertomp. PM sent!

On the engines the M38 used the 641087 casting thru about May 1952. The serial numbers on these blocks were MCXXXXX and the spare factory new engines stocked by the aArmy had serials within the same sequence but with the prefix RMCXXXXX. These early 641087 blocks had 4 freeze plugs on the right side of the engine and one on the aft side then switched to two freeze plugs on the right side of the engine and none on the aft side. In Dec 51/Jan 52 a test run of new style blocks with reinforced rear flanges was introduced. Then in Feb 52 the new style blocks became official but even though the Willys drawing showed the casting number was to have been changed to 804380 the foundry missed that and left the 641087 on the blocks through May 52. Supposedly the 804380 casting number appeared on the very last few M38's but no one has come forward yet with one in his M38. Every 804380 casting I have seen has had an RMCXXXXXX serial.

The original factory M38 wheel had the raised bead retainers on the bead seats, a 1/8" hole near one lug hole and were 16x4.5" with lug pattern 5 on 5.5". The only other Willys wheel to get the small 1/8" hole was the Willys truck/utility wheel which had no safety bead and was a 16x5" wheel. The original style M38 wheel continued with the M38A1. Eventually in the mid 60's or later the non-safety bead CJ wheel was often sold to the Army as a replacement.

Mark your calendar for the Armed Forces Day celebration on May 14-16 at Findlay, OH. There will likely be M38s there and several vendors, along with lots of owners to talk to. There are other shows in Ohio this summer. Check out the Ohio Motor Pool and MVPA websites.