$20k for a 1960's HD16 cable unit, really or the HD6G for $8500 but has a hydraulic pump seal out and notes it, again REALLY?  These are not mid 80's machines nor are they common for repair parts yet they want later model prices, good luck.  My 7G was running and a driver, weak but worked and for less than $3000 INCLUDING transport.  That was a few years back as well.  the 6G maybe worth $5000 running/driving and not leaking too much, the 15 or 16 may be worth $12,000 IF good rails, running, no real issues AND hydraulic blade but not these units, may be worth $8000 on a stretch.

Edgar I suspect is back advertising down at Lebanon MO, is a D7E old series Cat and well worn for sale there with what appears is his Phone Number.  Quoted as "Work Ready" but no real photos of rails, engine, control station or any hint at documentation of service records.  Shoes full of material in limited photos where cannot determine how much really remaining for lifespan and no s/n to research.  $20,000