Help me date this Deluxe

[Scott Spanbauer]

And no jokes about pickup lines.

This is a trapezoid-pickup Deluxe. Finally took the ashtray off to see what year it was, but I can't really figure it out. 4/51? 4/55? Do the big B and the #2 mean it was a second?

If anyone knows what is going on in here, I'd appreciate your opinion.

Thank you!

[Scott Spanbauer]

Actually, the more I look at it, it has to be 4/55. But I'm still curious about all the other marks and gouges.