Opinions on FirmFeel???

I've got a box with the small return line out of a 67 V8 Barracuda that I'd like to upgrade to take the place of the box in my 65 wagon (5/8ths return line). Since they're a vendor at the Nationals, I'd guess they'll accept my box at the show to save on my shipping charges. If so, wondering if I'd get my original box back, or is it just a core to them? Might have to give them a call this week to find out for sure.