Employee Stock Ownership Plan (ESOP) from 1980's. No cost basis shown in Box 5, 1099-B.

Last year I sold all shares I got from an ESOP program with GE.  I have had these shares since I quit the company in the 1980's.  Cost basis is listed on partial shares that were dividends since 2011, but a significant amount is shown in Box 5 as Non-covered securities with no cost basis shown.   Must I report all this income from sales and show zero basis?  This results in significant tax.