Hate to be a PITA, but you wouldn't have the "item no."by chance"; seems they have several available, but none that looks just like your's: of course their's are all on golf carts
Here's one at ebay for $79 but shipping is $18.00. You might find one even cheaper at EBAY. Just watch shipping charges. The one linked below is from a dealer with lots of good feedback.
So far as sizing, it looks like my store bought Kioti CK-20 roof measures very roughly
40" X 56" long. If anything, these golf cart covers are larger but work very nicely all the same.
Let us know how yours works for you, Patches. I'm sure you will be pleased. It is sure nice blowing without a face full of snow and also much nicer breaking the wind even though I make sure to keep the cab open at about boot level on down. This is the highly sought after method for keeping inside of window panels clear of condensation.
If you happen to clamp or bolt any pieces of lumber horizontally to fill out cab make sure to take a file and round off any sharp corners first.
BTW, here is one more cart cover with much more window area for $65 delivered to your door. This link will not last indefinitely as it is an ebay item. I have no personal experience with this one but see some of the folks are using ones like this.