For those that want to do their own service on their 68RFE, there is a little more to it than just dropping the pan and swapping the filters.
Your transmission, with the stock pan on it, holds about 17 qts of fluid. Only about 6 - 8 are removed by dropping the pan and refilling.
This leaves well over half of the old fluid still in the trans, TC, cooler and lines.......pretty counter productive if you ask me.
So, how do we get that remaining 9 - 11 qts out of the system? Simple, we use the transmissions own pump to get the rest out BEFORE we even drop the pan.....making the mess from dropping the pan significantly less.
Here's what ya do.....
1 - Remove the retaining clip and bracket on the drivers side of tranny.
(You'll want an extra set of hands for the next step)
2 - Disconnect the transmission cooler return line and attach a 5/8" ID hose to the threads. Place the hose in a container that can hold AT LEAST 5 gals, start the truck and place in neutral. This will start the pump and push the fluid out of the lines.
Once the fluid flow begins to sputter, turn the truck off to avoid running the pump dry.
Now, drop the pan and do the normal service.
Remember, the 68RFE has 2 internal filters, one is a pancake style that filters the fluid going from the pan up to the trans and cooler and the spin on filter that filters it after it returns from the cooler.
Also, the 68 DOES NOT have a reusable gasket like the 48 does. You will need some RTV to seal the pan to the trans housing.
Once you have replaced the pan and filter, there will still be almost 2 gals of fluid left in the TC, cooler and lines.
What you need to do now is this.....add a gallon of fluid to the pan and repeat the flush process above. Do it again until you see clean fluid begin to exit the return line.
Reconnect the lines, retainers and brakcets and refill as normal.
You now have 100% new fluid.