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i found out my block is crack beyond a good repair, but i finally track down a f head block. the original serial number was md 140171, but it looks like someone stamped an R in front of the # now it's RMD 140171. can someone id the year of this block and did they stamped an R because it was a rebuilt engine? thxs for any info.

All factory new replacement engines from Willys and Kaiser carried the R prefix. RMCXXXXX is a factory new replacement engine for a M38. RMDXXXXXX is a factory new replacement engine for the M38A1 and M170. LRXXXXXXX is a factory new generic replacement L134 for use by any of the flat head Willys jeeps and wagons and trucks.

It is not possible to narrow down the RMCXXXXXX engine to a date since the Army included several thousand spare factory new replacement engines in each of it's contracts with Willys/Kaiser and often in amendments to the contracts. A serious lack of contract info is the problem. The WWII people have just about all contract records for WWII production but since the government was only required to maintain a copy of contracts for 6 months after it's end we have none to develop a data base from.

thxs wesk, the R was'nt inline with the rest of the serial numbers that why i thought it might had been rebuilt. to me it look like it had been stamped after. but the goods news is it's standard!. thxs

Here are some examples:







If your "R" is drifting out by itself not aligned with the rest of the serial or is of a different stamp/font style then it was a field added "R" probably meant to indicate a field rebuild. The military did not do that. They installed an overhaul plate on the side of the block.