Mike,
You forgot the 2015 Winter SPAAMFAA Convention in Baltimore in March!!!
Alex, Mike is spot-on with his info. Allentown specifically has a great flea-market on Sunday. I've never been to Harrisburg, but I've sure seen the pictures. Awesome!
Deck gun? Forget the deck gun!!! Get that high-pressure manifold/hydrant on the running board! They're out there, but may be worth as much as the truck! ;-)
Hard Suctions are still widely available. Hold out on them until you find a set in good condition. You'll need to know the exact size you need, based on the inlets on the truck. (are you in the fire service? If so, I'm not telling you anything you don't already know - sorry).
Speaking of not knowing, us Midwest types can be a little slow: What does SLE stand for?!

And Generals made in Detroit are nice, but they're not as nice as the ones General made when they were still in St. Louis, until about 1933! Hah! The workers that stayed behind in St. Louis when General moved, eventually created Central Fire Apparatus, which survived into the 70s, and are well-appreciated locally.
Keep us posted on your progress, and post any questions - us firebolters need to stick together! ;-)
-Michael