With those years most of the bugs are sorted out, check all the vacuum lines, there is one vacuum elbow in particular on the passenger side of the throttle body that likes to develop a hole and will cause the engine to throw a lean code, but its an easy fix.
As far as trannys go they are both fairly solid, slave cylinders tend to be go out on the manuals but it depends on driving style and use. I have had 2 auto 4.0s with a combined 150,000 on them and they have been perfect.
hope this helps ya!
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2003 Ranger Fx4 4.0 TR- DBR long travel, Deaver G50, 305/70R16 MTRs, Supercharged, C4x4 bumpers, super sliders, 10K winch lots of lights and radios.