Value, $ 15k to $25k depending on condition, past useage and hours.
The 4X4 front axle is a wonderful option in your steep terrain, but examine the 4x4 drive train carefully. Part are available but very expensive. Check all oil seals for axle center, drop box, and planetary hubs. Open fill plugs and examine the oil. Sometimes owners will cure a leaking seal by pumping grease into the compartment, instead of the specified gear oil.
A 655D uses a 4 cylinder version of the bullet proof 3, 4, and 6 cylinder diesels that are used in millions of Ford agricultural and construction machines from 1965 till the early 2000's. Parts, including good quality, reasonable cost aftermarket parts are widely available.