We've just traded in our McKenzie Starwood 5-er for a 2010 3750FL Montana and kept the TrailAir pin box from the Starwood that we used just one season. Of course it won't fit the new Montana so we're looking to sell/trade it for one that will. The model type is "L03"
You can check the TrailAir website to see what else it fits
http://www.trailair.com/products/airpin/ap_appguide.pdf. Our cost was over $700 but we're willing to sell if for $400 or BO. Our new Montana has a Mor/Ryde pinbox which is great but we still prefer the TrailAir. So I guess we'll be selling/trading that one too