Take a look at the features you want to be able to tune with your new tuner, what is the best year of the 4.0L OHV computer for tuning?
Dont forget in 98 they all have PATS, so that becomes an issue.
What I am getting at is it may be really simple to replace your 95 PCM with say a 96 PCM, but the 96 PCM although OBD2 might not do as much as you think it does when it comes to the tuner.
So lets say you use a 97 computer in its place
Your 4.0L its self may have a couple/few sensors that will need to be changed out, maybe not. You will have to do some research. On the engine itself it is not likely, however the OBD2 PCM may use a digital crankshaft sensor (instead of analog) this kind of thing. This will depend on what PCM you get and what that year engine used.
The emissions system (EVAP) should be a real similar setup to your truck.
Your 95 has 4 02 sensors already does it not?
When I went from a 93 4.0L PCM to a OBD2 97 PCM I added the following to my truck to make it work:
fuel tank pressure sensor
EGR
4 ea 02 sensors
and I kinda "fudged" the EVAP system to eliminate a bunch of the hooey my 88 never had anyways (chacoal canisters, solenoids, etc)
thats about it!
best place to start?
Get the pinout for your 95 PCM 110 pin plug and then compare it to the PCM you want to use (97 4.0l OHV, 5 speed) and see the differences in the wiring.