RK 55HC,ym1700, NH7610S, Ford 8N, 2N, NAA, 660, 850 x2, 541, 950, 941D, 951, 2000, 3000, 4000, 4600, 5000, 740, IH 'C' 'H', CUB, John Deere 'B', allis 'G', case VAC
..kind should be a utf equivalent to m2c134d type oil ( i guess unless she has a TC ).. as to where.. have to look at your manual.. or the online parts diagram to locate the trans drain.. that or rickb likely knows.
Remove the pipe plug at the bottom of the transmission housing to drain. Refill with NH 134D or an equivalent oil. Dipstick/filler is accessed through the foremost of two small access panels in the cab/platform floor. You will not drain the torque converter, so if you have badly contaminated oil, plan on two or maybe three changes. Don't forget to change the filter.