78k miles isn’t a lot. However, if you pull a fair amount then it’s a good idea-not necessary-but won’t hurt a thing. Maybe just wait and get fluid here and there and change it at 100k. And do it yourself. I did all my running gear fluids for around $175 or so. Including an internal trans filter. Most local auto stores will take the old fluid too.
🤘 Kennedy fuel system support hardware, CCM front Diff Drop, some LEDs to make night into day, got some big ol 20's and wide ass tires and a nice display to show me what's up under the hood- 2012GMC2500CCSB