It looks like a Model 43 or pre-Model 43, and it appears to have an Aluminum cylinder too. I haven't looked at mine for some time. Seeing the pic of your gun got me wondering if these guns were made with both steel and aluminum cylinders... ? I seem to remember seeing at least one with a steel cylinder, but can't recall now. Anyone more knowledgeable care to comment?
Anyway, congratulations on the nice find. That one appears to be in very good condition. The number in the yoke cut (not "crane," unless you are a Colt man
) of the frame is not a serial number. It's a number used in production of the gun and has nothing to do with the serial number.