New to me Kubota KX121-2

I just picked up a used KX121-2 It is just going to be an around the yard machine. 3200 hrs with Cab. According to the dealer it was sold in 1998 by the serial #. It is not a " Super Series" My questions are, What is a Super Series anyway? Is there any out there making aftermarket pins and bushings? Any Advice on things to keep an eye on with this mode?. Thank you.

New to me Kubota KX121-2