I had an 1989 Ranger which I purchased from my Dad in 2002, was his new in 1989. I just did drop pan, change filter every 30,000 miles or so and the original transmission went to 269,000 before failing. I had it rebuilt and finally gave up on the vehicle at 336,000 miles, transmission still doing fine, too many other problems. Original engine when scrapped. Suspension worn out, front and back windows leaking during rains, rear main seal leak, etc. I would start with fluid and filter. Then if problems some transmission shops will do no cost diagnosis. How many miles on the transmission?