Here are the CC part #'s given in the manual for my 7235. Your tractor should be about the same as mine except for hp, both are 7000 series, mine = 23 hp (center number), yours = 30 hp, both are HST indicated by last number (5).
However, my tractor is older than yours, mine is a 1997. Don't know if they may have changed something in later model to require different fluid or not. But I also have a Cub Super Garden Tractor model 1782 that is also HST and the manual for it lists the same fluid as for the 7235.
Here are the #'s, all are same fluid, just different size containers:
737-3025 -- 1 qt.
737-3062 -- 1 gal. (Not in manual but bought from dealer)
737-3026 -- 5 qts.
737-3035 -- 5 gals.
737-3027 -- 55 gals.