Railroad Wrench Question

[hlszrs4]

I recently acquired two Railroad "Car Yard Inspector's Wrenches". Apparently these are not in the regular Snap-on catalogs? The one is a M-4431-A AAR with a clear 1952 date code -- a plain steel wrench. The other is a M-4431-B AAR with no obvious date code with what appears to be a darker, perhaps black oxide finish. The A wrench has 3 sockets and a 9/16" open end -- the B is similar but with an added 4th socket. I assume the B wrench was produced later, but how much later? Thanks for any help.

[snapmom]

I have a B with a 67 code. do you collect RR tools?

[SwensCo]

I have a brand new B model in the box that was mfg. in 1959 if that helps.

[Frank Murch]

Like this??

1977-Railroad-Tools-p 05.jpeg (2.24 MiB) Viewed 3298 times

[hlszrs4]

Thanks all, you guys are awesome. To answer snapmoms question, I have not really defined my collection -- I been collecting (really hoarding) lots of different types of wrenches, pliers, etc. for just a few years. I also sell a little to support my habit. Thinking of keeping the dated A and selling the B model. Thanks again.