Yeah, funny, unless you're the guy sent out to upgrade the KSU. Been there.
If you're running older software, (Which rev did they discontinue restricted? 6.1?) On the software card, you'll see "CICS X.X RP", or "CICS X.X SP". (occasionally they'd spell out standard or restricted.) RP=restricted
If you are running restricted, you'll have to upgrade to standard software, which allows for up to 24 exts, with the expansion card.
Try to get the same revision of sw if you want a smooth transition. Odds are, if you're running older software, your cabinet is rel 1. You'd have to replace the cabinet to upgrade to 7.0/7.1