Spark plugs

[TimK.43mb]

I have recently come across some spark plugs that I think are for the M38, M38A1, M37, M151, etc. They are the waterproof type. 3 different manufactureres, Autolite packed by Chrysler, Continental Motors Corp and Food Machinery. They are all dated 1952 and 1953. The Ordnance Number on all is 7525550. My question is, is this the right plug for the vehicles I mentioned above? They look like the ones I took out of my M151.

[Gummy1950]

I don't have the ORD book with numbers, but if the packaging is correct then the plugs go back at least to the M38A1 era.

[Cuz]

7524258, 2920-752-4258, MS35909-1, 2243, AR5S, WR44, XMJ-14 all fit the M38

8357724, 2920-835-7724, 2920-00-282-9135, MS35909-2, 2245, AR7S, WR46, XMJ-17 all fit the M38A1/M170/M151 series.

Other than being a single heat range apart they (top row and bottom row) can be interchanged up and down as needed. IE if you wanted a hotter or colder plug.

Your 7525550 became 2920-00-752-5550 which then superseded to 2920-00-571-6731 which has the following spark plug numbers assigned to it:
AVR3S
RML-12
RML-12
2344 Spec'd for the M715 Kaiser 5/4 ton
553086
8668752 Spec'd for the M715 Kaiser 5/4 ton
These are all 14mm x 1/2" reach which is too long for the M38/M38A1/M170/M151 series and I believe the barrels are sized differently so the M38 series cables won't fit in them.

I also noticed the 715 used the 2407 as well so the 2407 (Autolite power tip) would be the hottest plug for the 715 and the 2444 (Autolite non-resistor) the coldest for the 715.

[TimK.43mb]

Thanks to all for the information. I looked at the plugs again and saw that the length of the threads was longer than the plugs I took out of my M151. I am glad to know what vehicles they go in so I can target selling them to the right people. Thanks again.