>Joe I found the other number stamped on 6870-C is 3614.
Whereabouts did you find the "other number" Clint?
Do you see any circumstance where an owner or Museum would only be able to find the "other number" but not the serial number?
I think Claude must have provided the "other numbers" for those two, since I already have them in my notes. While the serial numbers are consecutive, it's obvious that the "other numbers" are not. ultimately, with ALL US built WW II AFVs, the owner would REALLY want to try to find the Ordnance Serial Number.
It would be nice to see an original M8 and / or M20 dataplate. An original plate would have the maker's name on there, whereas a remanufactured or rebuilt unit might just have "Ordnance Dept" or the name of the company or depot that did the rebuild. I'd be curious to know if the original dataplate might have "Ford Motor Co." in that great stylized logo of theirs. Pre WW II dataplates were made of brass, but the gov't later mandated the use of metal in order to preserve brass. One knock about Ford dataplates as regards the Sherman was that they were rusting & becoming unreadable a few months after they were made. It was recommended they be coated with some kind of preservative (lacquer?), but that probably didn't last long. There are lots of surviving Ford built Shermans around, but I don't know of a single example that has an original Ford dataplate.
>The serial numbers appear to pick up after that at 6624 & end at maybe 7050.
I was just making educated guesses about the second M20 Production Order the last time we talked about this a few years back. Since then, I did come across a doc which listed PO T-18402 as for 403 units S/N 6624 / USA 60131940 thru S/N 7026 / USA 60132342. So I had guessed right about the starting serial number. In the end, 427 units were officially accepted from this PO. By 1945, there would have been no earthly reason for the government to continue making these. Probably what happened was the government wanted to cut it off at 403, but Ford said they had another 24 hulls assembled & in the pipeline. The logical thing to do would be simply to tack the last 24 on to the end of the existing contract, & that's what I have done above with the guess that 7050 may have been the last serial number. However, from studying this kind of thing for the last 13 years, the logical thing wasn't always what was done. That's why I didn't want to dismiss 9793 that Robert B. reported, & am very curious about 4601.
Anyway, the highest Known good M20 Serial & Reg number I have in my notes is 7010 / USA 60132326. If we assume the logical thing was done & the series ended at 7050, it would be easy enough to set up a monthly production spreadsheet that would include the range of serial numbers & registration numbers assigned. I have the monthly production figures by Production Order. Sometimes overlapping Production Orders can be tricky, The only overlaps with the M20s occurred in March 1945 where 149 units were made on PO T-7227 & 14 were made on PO T-18402. T-7227 was completed in April when the last 4 units were accepted, & 146 units were accepted on T-18402. The overlap months are where you get the odd cases where a unit with a much higher serial number was accepted earlier than one with a lower S/N. For instance, S/N 3365 would have been accepted in April, & 6624 would have been accepted a month earlier in March.
>3504 has a listed usa number of 60131981 and as having side boxes rather than mine racks.
Assuming the Reg Number was found under the paint layers & is original, it would correspond to S/N 6665. I like to record S/Ns & USA Numbers from period pix where possible. The 95th Chemical Service Co used the one made right before that, 60131980, to test out a flamethrower in Pusan Korea, 10/52.
I would certainly think that the "late stowage" features would have been factory installed on all the units made on PO T-18402. Do you see any evidence of weld scars from mine racks on 6870?
Someone recently asked me if it would be possible to figure out the day of acceptance of a US built WW II AFV. Some Grant Medium Tanks & Cadillac built M5 Stuart series dataplates have been seen to have the actual day of acceptance stamped on, but most dataplates I have seen just show the year. (There's another reason why it would be nice to see what's on an original M8 and / or M20 dataplate.) The average daily method would probably get you pretty close, but I have seen clues in the docs that suggest that a miraculous number of units were accepted on the last day of the month, no doubt in order to meet quotas.