Good:
I'll try to help. Got any more info? Hours, condition, tranny type, pics, loader model, how many owners, make/model/condition of backhoe, type/condition of tires, 2wd/4wd, clutch type. Does the tractor say "EverClutch" on it? That would be a plus, but that might have been available only on the later L-50s, the L4350/4850/5450. Those came out around '91, the 4150 around '84, so it's gotta have some hours on it. If it's the same basic frame as the later LXX50's, it's built like a tank. maybe do a search on 5450 and read some comments by a well-known owner of one.
15K is probably going to be a little on the high side from what little I've heard, and based on what kind of new tractor and backhoe you could get for about twice that, like an L4330 with a Woods/Bradco/Kubota backhoe.
Hope this helps, John D.