You don't have SX3300s. I think, for whatever reason, you're confusing SX2000 and 3300 variety switches. 3300s come in several flavors (AX, MXe, CX, CXi, LX..probably more), but definitely not SX3300...or at least not that I've heard of. I've been wrong before though...once or twice.
I'm not entirely certain how to tell if switches are clustered, in fact I have a very rude understanding of what it means to be clustered. However, I'm fairly sure that each switch in a cluster has a unique numerical identifier within the voice network, that unique number is used so that the switches can reliably and more directly route calls in your network without the need of ARS, and the clustered switches update eachother when programming changes are made. Do you have anything like this in your programming?...I'm sorry I couldn't be more helpful, I need to go study up on clustering as I'm just a few months away from clustering my network. Of 34 switches. *gulp*