This truck as 260k mi on it. Transmission was serviced by previous owner at a dealership at 199k mi. Paperwork says "Flushed; added 14 qts" so I assume they used a machine since only a couple of quarts come out with drain/fill. Question: With 60k miles miles on it since previous trans service, what should I do? Drain and fill at the next several oil changes? Flush and fill (assuming I can find a good deal on ATF)? Leave it alone? Hope to keep this truck for a long time as it runs well. No transmission failure symptoms apparent at this time. Thanks!