The first design used "=R2=" cast in the radiator top tank and no radiator side tags. The second design used "Caterpillar" cast in the radiator top tank and "R2" radiator side tags. I'm not sure of the S/N at the change, but it can be determined by studying the parts book. However, if 5E3544SP is correct, then your machine should be the same (since your's is a lower S/N). Your entire radiator may have been replaced sometime in it's life.
The large brass cast tags were used on many tractors: 22, R2(5E), THIRTY(6G), R5, RD4, RD6, RD7 and RD8. The 22 and R2(5E) used the brass tags to end of production. The THIRTY(6G) was converted to the stamped steel R4 tag at the time of the name change. The R5 brass tag was converted to the stamped steel R5 tag in October 1937. The RD brass tags were converted to the stamped steel D tags at the time of the name change.
serial#5E3501-3534 had a special block lettering "caterpillar" on the top, serial#5E3535-3553 has the "R2" across the top , and serial#5E3554-3583 has the brass tags on the lower rad sides that say "R2". Hope this helps . thanks leroy
Hmmm.... the last two threads point in completely opposite directions. I suppose the machine coulda had a replacement rad,, but still unsure which is the correct one... Both my sources in this thread are experts, I am leaning towards casting/ finding a brass plate , unless i can find a R2 top tank first... still unsure ... anyone else want to weigh in on this??? better yet, could someone tell me what radiator setup you have on your R2 5E , or best yet tell me you have the brass plates and /or tanks for sale... dave