Keyton,
I apologize for being harsh yesterday.
My 1952 diagram book also states that these tenders had a coal capacity of 16 tons. That number is quite co-incidental, as yesterday my local radio station played Tennessee Earnie Ford’s “Sixteen tons”. Anyway, it appears that these engines kept their USRA tenders their whole life; I say this because they all still had their original tenders in 1952. Well, sort of. The six O-3’s shown each had the following tender numbers:
3200–tender #3208
3201–tender #3205
3203–tender #3204
3204–tender #3200
3207–tender #3206
3208–tender #3202
So, it appears they kept their tender class, not their individual tender. Now, if you’re in the mood to keep your engine in the “as delivered” state, I’d recommend going with the “16 tons” and “10,000 gallons”. And, of course, the engines were delivered with the “normal” number.
Something also to consider is that they were delivered with their air pumps mounted on the side of the boiler, but the pumps were later moved to the front of the smokebox.
I think we are both finding that it’s tough to find a picture of the rear of a tender (just try finding one of the FRONT).
I found a few pictures of the rear of GN tenders:
p 134 of “Lines West”–old picture of #3353–no lettering showing on rear
p 14 of “Great Northern Steam & Electric in Color”–#896–no lettering showing on rear
p 15 of same–#1453–numbers on rear facing headlight and two signs saying “LOOK OUT FOR OVERHEAD WIRES”–no other lettering
p63 of same–appears to be some lettering but I can’t read it–it’s very fine–it’s a big vanderbilt tender
I think it will be tough to come up with “proof”, but I think I’d go with no lettering on the back wall of the tender, ESPECIALLY if I was doing the engine in its as-delivered style–the theory being that railroads tended to add lettering over the years–the word “theory” should be noticed.