They are several youtube videos on how to do the gears. I've thought about changing to 4.10's and doing them myself. I don't have a gear puller or dial caliper. I think you can rent them from local parts stores but also a part of me keeps telling me 'its over my head and i'll mess them up'
. I've installed everything i have except for the gears. I had my local Ford dealer install them for $550 labor
. I didn't trust any local shops.
If you feel like you can do them yourself, do it. Just remember the fluid stinks very very bad