A Prewar Engine Question

[envfocus]

Is there a way to tell by just looking at the underside of an "O" gauge, Lionel #253 Locomotive whether it is a 253E or just a 253?  I am aware that this type had either the "E" added to the brass insert or the letter "E" was rubber stamped on the side.  The one I've found has a lot of paint loss where the "E" would have been and no "E" on the insert.  It does have a manual reverse knob, but is there something I could see that would tell me it has an "E" unit?  Any help is much appreciated.

[jimrice4449]

I haven't got the foggiest idea but I'll bet there are a bunch of folks over on the Classic Toy Trains forum that do.

[envfocus]

Thanks. I will post my question there.