need help identifying gas cap

[mot]

i have a gas cap that is stainless and looks like a model A cap
but the largest diameter is 3 inches and the lower diameter is 2 3/8
it is vented and has the intials EDM in the center
any ide what it fits?
thanks Tom

 

[TK in LA]

Looks like 30/31 "A" to me

 

[mot]

i thought it was a model A also when i bought it
but it is smaller than an A cap
heres three more pictures,
the original A is on the left and the unknown is on the right
since it looks so much like an A cap,i thought it might be off of an early V8
tom

 

[mike@earlyfordstore]

I wonder if its an original Model A radiator cap that somebody vented to use as a gas cap?