I tend toward Sea-Doo; Arctic Cat stopped making the Tiger Shark quite a while ago...as you know. I would recommend that you just measure them. You can measure the length and cicumference around the bar. Note that the diameter is then the circumference/3.14159. {You might just be able to measure the diameter at the end of the grip...it looks open}
With aftermarket, you might have to make some modifications to deal with the rivit. Clearly you will have to drill a hole and might want to countersink and use a washer. The grips that you are looking at are specified to be 7.5" in total length and 2.5 " in outside diameter. I do not know what the inside diameter is. If you are going to buy these on ebay ask the seller to measure them for you.
The 964 appears to be a shorter grip (FYI)
http://www.motorcycle-superstore.com...57879-3729315-
Jetskier