Kip,
For what it's worth, when I had my '46 (with a '41 cab, so whatever) rewired the guy that did the work suggested I install mid 70's Ford (ugh!) twin horns. They are LOUD and sound right. They look much like the ones in the link from TxLaTx above but I put them behind the grill instead of in the engine compartment. Besides, I've got a 350/350 and IFS/IRS so authenticity is no longer an issue.
