Antique Snap On rolling tool box

[jsalvador]

Can someone help me identify this toolbox ? Year and maybe model number?
It has a power plug in the side, is that a factory thing? If so what sort of plug will it need?
It is also missing several of the bottoms drawers, any idea where I could get them ?
Thanks so much.

 

[cgrutt]

Possibly KRA300D. Pic below is from 1973 catalog and shows bottom 3 drawers, roll doors and light/electric were optional. Believe that logo was used 1960s - 1970s possibly earlier.

 

[MAD]

The power inlet looks like it might be a ML3 midget locking connector.

 

[1982fxr]

Check the back for a stamp