Cowgirl,
Ive got a 2005 5740C and I believe your transmission fluid add point and check points are in the same place as mine. First of all, they ARE NOT located in the exact same areas. On my tractor I have a front end loader and all the hydraulic hookups in the back for a back hoe attachment etc. All hydraulics are connected to one hydraulic fluid reservoir, if you will, including your transmission, power steering, front end loader, etc.
Directly behind my drivers seat, on the outside of the back window is an aluminum tube coming up to about the bottom of that back window. That aluminum tube has what looks like a black rubber sink stopper sticking in the top of it. Out of that black rubber stopper top is a small aluminum tube about a couple inches long and it attaches to a clear plastic tube of the same diameter. Pull out that black stopper and that's where you put in any new, additional hydraulic fluid in my 5740C.
Now, go down to just about your back axel and look for a dipstick handle. Its usually covered with dirt and grass on mine. Clean off dirt and grass completely and using that dipstick, check your hydraulic fluid, thus your transmission et al fluid on mine. Hope this helps. BTW, my dipstick is on the right side of the rear, above the axel and transmission. Need any more help, just ask,