The '89 I have here is a 3.0L. The engine on this particular truck has actually been fine, most of it's issues have centered around the accessory drive items I mentioned & wiring (intermittent lights/gauges, etc.).
My friends' were a mix of both engines. One had his engine rebuilt 3 times because it spun a bearing at 80K miles, and then subsequently couldn't keep head gaskets in it for the next 5K (indeed it was a 3.0L). Again, it wasn't just the engine though... The transmission had a couple issues, front IFS axle problems galore (busted parts, wouldn't keep alignment), wires in the steering column that fatigued and broke where the tilt column flexes, blower fan quit, engine stalling because a terminal on the ignition module corroded (bad water seal around the plug or something), it just went on & on & on & on with this truck.
Two other buddies' trucks were the 22REs. I don't recall too many issues with the engines other than one was a chronic oil-burner (even after a rebuild) but again it was the other stuff (birfields, steering arm, one lost a transmission, power steering leaks, wiring, axle knuckle-ball leaks that repeated attempts to fix kept failing... I think one had wiper problems too at one point, I seem to recall something in the linkage broke).
My Fords have had their share of issues too, but not like this.
The 2.9L was produced by Ford in Cologne Germany.
http://en.wikipedia.org/wiki/Ford_Cologne_V6_engine
I don't know of this "main bearing" is you speak of (never heard that one before), what the 2.9s were known for was head cracking (almost always a result of overheating the engine, which it didn't take much... one stuck thermostat could do it). Their bottom ends however are bulletproof just like many Toyota fans will swear a 22RE is. You keep on top of the cooling system and they typically go 300K+, just like the 4.0L that evolved from it (it should also be noted the 4.0L heads were much less prone to cracking, making a 4.0L that much more solid of a design).