I've got a piece of vintage literature (A radio install manual for a 1940 Packard) and wonder what Packard clubs are around or best way to advertise it beside the HAMB classifieds?
There's a national (probably international) Packard club. I'm sure they have a website and classifieds section. Do a search on the web. There's a huge following for these cars. Their owners are a very enthusiastic bunch.
A quick search revealed 3or 4 local Packard Clubs right there in Texas, maybe more. One is called Lonestar Packards, I think in San Antonio. There's also one in Houston and others, perhaps closer to you. Google is your friend. I'm sure some of these folks would be interested in your radio install manual. Good luck.
The AACA will reach a lot of Packard folks. Here is a link to the Packard section: http://forums.aaca.org/f134/