how many different kinds of caps did they make ? I have several and it seem most of them are different in some way or the other .I have b8100 a2 ,one that appears to be made of solid br*** no numbers very heavy duty,center is braded in with the 2 smaller early model tabs ,another one made of br*** with b8100 a2 with screw in center, one with little round symbol and a#2 all are old .
There were 2 radiator caps produced in 1932,,a p***enger car cap B-8100-A was chrome plated zinc die cast,,the detachable hardware was made of br***. The other cap was for the commercial vehicles B-8100-B,,it was made of br*** with a skin of stainless steel with a smooth top and knurled edge,,the inside hardware is riveted. There was however a second version for the inside of the p***anger car cap to prevent it from being installed backward,,this came along in the late summer of 1932... Reproduction caps have been around almost from the begining.HRP
The version designed to prevent putting cap on backards had same casting, the little inner cup got one oversize lug on it so it could only go one way. Supposedly seeing his cars with cap backward annoyed Henry, like those Honda kids now with baseball cap backwards... Cap works fine either way, and of course removing one screw allows you to reverse the wrong-way preventer...but if you do that, Henry will send over Mr. Bennett to break your legs.
Here is a thread I started on the Ford Barn with pics and a drawing from DavidG http://www.fordbarn.com/forum/showthread.php?t=157513