Aww that thing looks pretty good, $500 well spent IMO.
The 5-speed tranny really broke?
I'd say look for a new one, although $500 isnt horrible. When i went 5-speed shopping the junkyards near me wanted $800. That was unacceptable, since i got a brand newly reman'd unit for $750 right down the street =)
The Transmission is the most unreliable part of these trucks, and thank goodness you want the 5-speed and not the automatic. The engine is a beast, and the axles are pretty stout. The front end might have some alighnment issues (nature of the beast), but all in all this truck will make you very happy. If the 5-speed you find is in good shape, it will only need to be replaced once. Im surprized you even need a new one. Most the 5-speeds dont blow up unless you abuse them. (IE 33" tires and stock gearing)
But keep in mind, if you replace the tranny, you will want a new clutch to go with it.
P.S. Make sure your hubby and dad put ATF (automatic transmission fluid, Dextron III, Mobil 1 syntheic is the best) in the tranny and not GEAR OIL.
Ford used this tranny, along side another 5-speed tranny for many years (before the explorer). One used gear oil, and one used ATF (our 5-speeds). Most explorer books STILL lists the other 5-speed (even though it hasnt been used in any ford vehicle since like 89'), which confuses people. And the fact that a manual transmission is supposed to take Automatic transmission fluid seems to confuse people even more. So dont use Gear oil! haha