Oops, sorry it is the 460 and an automatic. How would I tell if the odometer has rolled over or not?
For comparison, here are a couple other trade offers I've received: 92 Chevy 1500 Scottsdale 4x4 regular cab 350 auto 123k miles. 97 Ford Explorer XLT 4x4 4.0 V6 auto 188k tow package.
No way to tell on odo rollover. If it's an automatic then it's the E4OD. It's bulletproof presuming some basic level of preventive maintenance. The E4OD is an outgrowth of the sledgehammer-reliable C6, and I've seen bone-stock junkyard C6's hold in excess of 600 hp without so much as a whimper. The E4OD is essentially an electronically controlled C6 with an added overdrive stack. Many of the internal parts will even interchange.
Almost forgot, plan on the 460 using a good bit of oil. 460s of that era had piss-poor valve seals and would begin leaking oil through the exhaust side. Not a performance issue, though the excessive oil use will eventually kill the converters if it's still so equipped. Fortunately valve stem seals are an easy fix and the seals are cheap. The expense will be shop time, but it can be done in a couple hours and doesn't require removing the heads. It does require removal of the rockers, and a cylinder pressurizer, but other than that it's just time.
The other two choices, I don't know. The Chevy will likely need the 4wd actuator replaced, that is if it hasn't been already. The linear actuators are a known problem. Tallpine had a thread about one on his "new" truck just recently. Replacement motor-driven actuators are readily available, as are cable operated manual conversion kits. Again, easy fix, relatively inexpensive, and it can be done in your driveway with basic tools. The engine is probably a garden variety TBI 350. Kinda hard to go wrong there. IIRC it's the L05 variant which I think was used from the late 80s up until they introduced the Vortec motors in 1996.
The 4.0 in the Explorer is a good engine, about as solid as you can get. Ford made a gazillion of them. I guess it would really depend on how well it's been maintained. Their only real weak point was the oiling system, and only because the way they oiled made the lifters and upper valvetrain somewhat sensitive to oil contamination. If it's been serviced regularly you're probably okay. If you hear excessive valve train noise, steer clear as it likely needs new lifters. Expensive fix. Aside from that, they're pretty hard to hurt. I've never messed with the rest of the driveline in that vintage Explorer so I don't know anything about the tranny, transfer case, etc. The rear axle should be a Ford 8.8 which is a proven commodity, though high mileage units may need new bearings or axle seals. Again, easy fix and parts are everywhere as variants of this axle were (and still are) used universally by Ford in all live-axle rear-drive applications except Super Duty trucks.
What are you going to tow? I guess that's the big question. If it's the occasional utility trailer then any of the choices would probably be fine. If it's a larger rig, go for the full size trucks.
Brad