The C6 has very few problems compared to other ford transmissions. One of the problems are hard shifts going into reverse. That is nothing but a simple adjustment and is not a concern. Secondly, all of the fords have front bushing wear, there's really nothing to do except get it updated.

Next,
The worst thing you can do is buy a truck that has never had the fluid changed (like mine)and change the fluid right away. People think because the fluid is not cherry red that is has to come out. The fact is that the detergent has been broken down and the tansmission has a lot of material building up. That is not a problem. When you replace the fluid/filter, the detergent additive is restored, cleaning all of the material off of the vital parts, sending it to the valve body/ control section of the transmission where it will soon plug passageways and valves. That spells overhaul time.

So, if your fluid has been left in for more than 30,000 miles, then the only thing you can do is to put a big cooler on it, change the filter regularly, and replace with the same old fluid that came out, adding a quart of new fluid when needed. Keep it until it blows, which will be over 150k.

If your tranny is well maintained, then change the fluid and filter on schedule and you will never have to worry about the above.

I have personally ruined 4 trannys for changing the fluid because it was not cherry red. 2 chrysler caravan trannys, 1 E4OD, 1 chevy od in a k2500. I got to spend 3 hours with a rebuilder at Aamco, he explained all the basics of the trannys and the do's and don'ts.

One final remark. A neglected C6 still has the potentail of lasting 150k or more with no problem if it is not overloaded or horsed on.

Sorry for the long novel, hope this will help some

1986 F-250 6.9 diesel,4x4,XLT Lariat,Ex Cab, 8'bed,etc...