Weak points depend on the number of hours and the condition of use it has received. Since it has not been used for 8 years, drive belts would be the first thing I look at. Being shedded helps, but that's a long time. Engine coolant is probably low, bearings are not going to show themselves until about 1-2 days of harvesting - then watch them carefully! On the lighter side, the K2 is a good solid combine. The corn head and platform is where I would concentrate. They could have worn parts such as wobble box or pitman arm bearings_ball joints for sickle, or bevel gear drives in corn head units. Did your neighbor service it regularlyIJ That's worth a lot. Price for 1978 k2 diesel combine with platform and assuming 1500-2500 hours, air conditioning, heat, and chopper in good condition should be near $4000-$5000. If it has a hydro-fold unloading auger then add $1000 to price. The corn head depends on if its black or orange. If its a newer A330 black w_stripe its worth $2000-$4000. If its 1978 black A330 in good condition it should be worth $1500-$2000. If its orange then it's usually sold with machine_platform at no additional cost. How good of a neighbor is heIJ Best situation - can you pick corn with it for a day then price itIJ Good luck!