1937 S/42 S/n question (with pic)

[Zamo]

Hi all, first post. I've just decided to get back into Luger collecting (small scale), having had a 1937 S/42 and a 1920 Commercial in the past (back when they were a lot cheaper).
I am looking at another 1937 S/42, and it has a strange S/N on the frame.
It looks like the lowercase alphbetic range stamp is either mis-struck, over-struck, or just "weird". In the photo below it shows what looks to me to be a "u", but the seller is calling it an "a". It came to my attention when he said that the finish is "Late style" 1937, that is all blued, with no straw. If it were a "u" I would think that would be correct, but if it's an "a", shouldn't it be strawed? Granted, I am a newbie here, but it's my understanding that this s/n 3746a would be pretty early in the 1937 production. If it was 3746u it would be much later. It's not a cheap Luger, and he's claiming it's the original finish, so that's why I thought I'd seek out some help from those in the know. Here is the photo the seller has provided:


Any one here have any experience dealing with Les, at Kustom Kraft Gunsmithing Corp. of Columbia, NJ? He seems alright, and has very good feedback on GB, but I am a little concerned. I've already past up a lot of really nice "refinished" Lugers because I wanted something better. I don't want to pay MORE for what I could have gotten for much LESS. You know. Same old deal.

Any help would be appreciative on this.
Zamo
Olympia, WA