68rfe Service?

So I bought a 07.5 6.7 with a 68rfe. It has 108,611 miles on it. I couldn’t tell you if the trans has been serviced. I am wanting to completely drain as much of the fluid out and refill it with new fluid. Does anyone know how to do this without taking it to a shop. A buddy of mine has had a couple 48re’s and said he takes his trans cooler line off and drains most of his from that after he has taken his pan down. Will that work on the 68rfe’s? I have read that I should never get the trans flushed cause it pulls debris and dirt through everything which causes issues shortly down the road. I hope someone has a way to do this. Thanks