1994 rx7 corrosion under engine, SC
 

Hi...
im looking at a 7 in SC. I did a VIN check and found that it was taken in for a pre-but 3 wweks ago and was found to have corrosion under the engine. If the person that had this pre-buy is on this forum..please let me know. and to everyone, how big of a deal is this? What corrodes under the engine...the engine itself or some form of protective shield? How should this impact a purchase?
thanks:confused: