does anyone know how good these engines run?

the 3.1L is the stroked 2.8L GM motor. i had one in my 91 Rodeo (3.1L) they run forever BUT have NO POWER at all. only 120 hp and 165 ftlbs of torque. 2 issues with that motor, lifters mushroom from wear near 80k and intake manifold gaskets can let loose and mix oil and antifreeze (more common on the older 2.8L though). most 2.8L accessories bolt right on, cams, headers,valve covers etc....parts are CHEAP AS HELL for it too. a better upgrade is a GM 3.4L but minor machine work is needed for the starter placement (has to switch sides, drill and tap, not difficult if you know how to drill and tap 2 bolts for the starter). that motor pushes 160hp and is in many Camaros. that 3.4L also has some support for aftermarket parts easily making 180-200hp and again GM, parts are cheap

sweet, would you suggest getting one for a p'up?

no, this is what i suggest

http://forum.planetisuzoo.com/viewtopic ... 394#145394

seriously, 190 hp out of the box 3.2L but there is no aftermarket support for these motors. and at that point just buy a 93-97 Rodeo...
the GM 3.4L is the way to go

that looks sweet. i like the passport dash.