Even though we are the Classic Tailgaters and the majority of our trucks are in the 50s we don't have a hard cutoff. We "encourage" (and seek) trucks 25 years and older but are open to anyone that enjoys being around and working on trucks. When we started someone was worried that the a tuner truck might join. We decided that would be ok and as long as they wanted to listen to the old rusty stories, the more the merrier. Did you see my new post - Successful Truck Show? That show was open to all trucks.
Anyway, just keep hitting up the classic trucks you see and it will come together. We have a great core group of about 15 to 20 and will continue to be truck friends (club or no club). Our dues are $10 single and $15 family. This was decided on just to have money to make copies and send out letters as needed.
Good Luck! Buddy
ps - I'll be headed for NA for a little deer hunting in Dec..