Easiest visual inspection are the motor mounts. Look for corrosion. Is these are corroded to the point you can't see making adjustments by backing the nuts, then you are looking at short of $1,000 in parts just for the four mounts. If the boat is out of the water look to see if the shaft is brass (original OEM) or stainless steel as well as any play in the cutlass bearing. This little endeavor, for which I knew of before purchasing an otherwise fantastic '94 boat cost me $3,200 to include labor, a portion of which I negotiated off the asking price. All this is normal wear and tear on boats of this age. It's just a matter of when it gets taken care of - before or after sale...