I recently purchased a 97 F350 7.3. It has high mileage, 280k and I don't have any records regarding the service the tranny has had. I Have heard it is unwise to change fluid and filter in a tranny if it hasn't had a fluid change in quite a while. The fluid does not appear to be burned but it's hard to tell. Should I just keep driving the truck keeping an eye on the fluid level? One thing I have noticed is the that the Trans shifts pretty hard. It isn't erratic though. Any input is much appreciated thanks!