How to identify a radiator cap from the 1930's?

I've been trying to identify this Jarvis #959 radiator cap, and I'm coming up empty. It has a Patent Pending #1683083. It's 3 3/16" wide and 7/8" tall at the fin. It's heavy...weighs about a pound...anyone know a website that identifies these old things?

 

http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=270941976507&_trksid=p2992.m753 and item #270947362887 I typed jarvis rad cap in google and came up with these...JOHN

 

I saw that, but it's not a 1932 Ford cap...he also had a 1932 Chrysler, Dodge, Plymouth cap for sale that had those exact same three pictures in that auction!

 

Cool deal, Thats all I could find. I figured you Had seen those...JOHN

 

Heres one that they claim to be a 30 plymouth

http://forums.aaca.org/f170/early-30s-radiator-cap-id-help-266293.html

 

I did not look at the link, but I will say it is right around 29 or 30 Mopar. Late-year 29 DeSoto Model K had a single fin like that, but I don't recall those extra detail lines...but it's been a long time since i had one. Early 29 DeSoto Model K did not have the tailfin like the later 29 did. See if you can find one online.

 

Much obliged guys...