I'd have to say between 4 - 6 hrs @ $175 an hour in my area! It's not that bad of a task to do. I checked mine around that 150K time frame. Was still in spec and will revisit again around 300K.
With all you've done on your trucks, this should be well within your wheelhouse!

I try to turn the wrenches on mine for as much as I can. I know that there will come a time when that will become difficult and hopefully saved enough to then pay someone to turn the wrenches!