That kart looks like a home build and not a factory built kart. BMI, GoKart Supply, MFG Supply, Azusa, Amazon, Go Powersports and a ton of other places are going to be your best bet for parts. And get rid of those Harbor Freight hand truck tires!
Welcome to the forum. You didn't really think there were catalogue parts available for that, did you? Most all parts are generic. If it fits, then it's the right one. All of the places mentioned in the post above by Denny will have everything your kart needs.