I know that they're good trucks, but unfortunately, Ford has seen fit to discontinue its manufacture for sale in the USA. It will continue to sell overseas versions with the diesel engine that we can't seem to get here, even though it does get in the low 30's mileage wise. Ford's excuse was that more people would be induced to pony up the money for an F150 if the Ranger wasn't available, but at the prices for which I've seen the F150 selling, I rather doubt it.
As to the durability of the Ranger, an old acquaintance of mine used to run them in the HDRA circuit, and his pre runner was used with little modification of the drivetrain. He did mod the suspension to give it more travel and clearance, but the motor/tranny combo seemed to run without alot of extra maintenance. It was a Toyo manual tranny, and seemed to take the abuse in stride.If I recall, the Mazda "B" series truck was/is the same truck as the Ranger, but I could be mistaken.
IMO, if the truck is in good condition, it should give excellent service.