Theres a difference. The 604 was a piece of trash. It could have been filled with magic, and half would have failed. Changing the fluid every week on a 604 was not really going to extend its life. We're talking about a properly engineered and assembled modern transmission vs. a cheaply engineered and built 30 year old unit. The fact is that ZF transmissions will almost always last the life of the car without a need to be serviced. Im not saying to NOT service it... it certainly wont hurt anything. But its not 100% necessary. The engineers know that changing the fluid has not inherently extended the life of their transmissions. Of course, change it if it gives comfort! Piece of mind is definitely worth something.