The uncovered shares means they were originally purchased prior to 2012.
you can google the name of the mututal fund and its symbol and with any luck Yahoo! will have the price on the date you originally purchased the shares.
"Uncovered" simply means that Vanguard is not required to send the cost basis information to the IRS. I suspect you moved this position to Vanguard sometime after 2011
Vanguard's MinTax is going to sell the lots that have the HIGHEST cost basis / share. It is that simple.
