I'm pretty sure there is not serial numbers on pumps. Here's what you can do click on "PARTS" top of this page then find the year and model of your ski, click on Propulsion External, this will bring up a diagram of the pump, enter 1 on the corresponding part number and click add to cart, this will bring up the part number.
Once you get the part number, just google the part number, it should give you corresponding skis.
Most 90's models ski's use the same size pump, it varies in construction, plastic, aluminum or bronze.
Lou