Ok, might sound a bit odd this one, but where is the chassis number on a '41 66. Is it the small plate above the Body number plate on the firewall/bulkhead, that starts with '66'??

 

I'm not familiar with a 41 but on later cars it's located on the drivers door post just below the hinge, May be different on a 41....Tedd

 

I am going to assume that the chassis number will be the same as the '40's, a metal tag riveted to the frame on the driver's side just aft of the forward crossmember on the top side of the frame. Should be stamped OMW followed by chassis #. Look just under/behind the generator..