Never changed gear oil myself before - difficulty?

Vehicle: 2004 WRXI have a good bit of automotive experience. 10+ years doing a lot of things. Swapped springs/struts/coilovers on about 8-10 cars, swaybars, more oil changes than I can count. Pulled 2-3 engines and transmissions. Radiators, hoses, little odds and ends. Other random stuff.But I've actually never changed gear oil. I had it done by a shop when I purchased the car used a few years ago and it's now reaching 35k miles, so it's time. Car is autocrossed too, 20+ events a year for the last 3 years.Going with Motul for the front and rear diffs, Subaru ATF for the tranny as it's going to need to be drained and filled 2-3 times to get enough new fluid in there. New tranny filter.Anything I should be concerned with? Or is this as simple as an oil change? The thing that bugs me is the location of the dipsticks on the tranny and front diff - it's super hard to get the fluid in the dipstick holes it seems and there's no fillter neck on those parts. Probably going to do the ATF fluid every oil change as you only get about 4 quarts out of the 12 full capacity each time. Supposedly it should be changed every 15k in hard driving too, which this car experiences.134k miles and just want to keep everything in top notch shape. via /r/cars http://ift.tt/2tiC027