It appears that this is certainly pre WWII and what I consider the better Model 37s. Red Letter means the word WINCHESTER on the underside is hilighted with red paint. Don't see it but I have a 20 that has only traces left.
Yours appears to be in good shape, like mine and I would not hesitate to use it with 2 3/4" loads. Around here folks want around $200 for these things but I think thats to much. $150 is more reasonable to me, but thats here. Can't say about your area. I think they are good guns.