There is more than one style transmission in the 1760's. I'm somewhat familiar with the old style, no reservoir, just a vent tube runs up high with a clamp and a vent on it.
I do not do PM's anymore. Hundreds and hundreds of tech questions, I ain't got time to answer them all.
The filter is internal. You have to remove the transmission and partially disassemble it to get to the filter. Most don't bother with them. The filter is just there to catch any metal filings that were left from manufacturing processes.
Noise can be caused by a thousand things.
Change the fluid. If yours doesn't have an external spin-on filter, it's the early style, which you have to physically remove from the tractor to drain it. That or disassemble it. They aren't really serviceable and I do not know if the filter (or any other part) of the transmission is still available. 20w50 works best and is what the work shop manual calls for. Synthetic is quieter, and I think Hydrogear even has their own 20w50 hydrostatic transmission fluid. I have not ordered any; it's rare for us at the shop to get a request (or approval if I offer) for a fluid and filter change based on cost. Those old riders take a while to change the fluid & filter if we have to remove the transmission....and that doesn't account for any broken fasteners, and seems like there's always one or two, adds cost (labor), unfortunately.
If it's real noisy, like abnormally, you might try topping the fluid level off which I think (IIRC) can be done in the frame. Grab your work shop manual for YOUR tractor (T1760 and T1760A are a little different) and get after it.