I have a 95 B4000 4x4 4.0L
Is it worth the time and effort to swap for a Sohc engine.
1. if so, are they all the same or is there a desired year SOHC.
2. does it bolt up to my 95 5 spd manual?
3. are there PCM/ECU issues?
1. The early SOHC engines had issues with chain guide followers self destructing - which requires pulling engine to fix. Most have either failed and been fixed, been fixed before they fail or newer design (which although much less likely to fail, should still be updated regularly to avoid issues).
2. Yes, SOHC would bolt up to your existing manual. There are flywheel/crankshaft differences, so your existing OHV flywheel won't bolt up. And there will be 1 bolt hole in the block that there isn't matching hole in transmission for; it's not absolutely required.
3. Your existing PCM would run the SOHC, but it wouldn't take advantage of the fact that SOHC can/needs to rev higher to make the additional power. A tune can help this, but you won't make full power this way as the older PDM can't accommodate the additional knock sensors of the SOHC. Alternatively, you can use a SOHC PCM, and tune out the PATS and dashboard functions (I think ideal, in your case, would be '97 Explorer SOHC manual PCM, but good luck finding that).
3.1. There are aftermarket supercharger kits for 4.0 SOHC (thanks to it being in Mustangs as well) and they will certainly help with power...if adding cost.
4.1 Transmission is non-starter for V-8; it won't bolt up.
4.2 We would need a little more information on whether the truck as 7.5 or 8.8 rear axle to make informed decision on axles
4.2 Transfer case holds up OK, so long as not too heavy on skinny pedal, but there are better options