i change ALL my fluids after every wheelin' trip. If i don't go wheelin for a month i change it the first day of the month. I do this to reduce the risk of getting water into very pricy parts that could cause them to break. Thats just the way i do it. Other may do it different. And don't forget the GM posi fluid if you have it. Hope that helps.
91 S-10 4.3L, 5 speed, 3 inch bodylift, 32" super swapper TSLs, 2 inch rear shackle lift
73 CJ-5 mods- way too many to list
91 Yamaha Banshee
00 Kawasaki ZX-12