This van Dam FB8, margin block of 6, features the elusive FB8a, which is the "Feather In Bun" variety, which is found in position 29 of the sheet.  These stamps are from the 1864, 1st Issue Canada, Federal Bill Stamps, which were issued in 1864.  The FB8a stamp rarely appears, so grab this block today!
 
This FB8/FB8a (MNHOG) block features stamps in the positions of L29 (MNHOG has a premium of 200%), L30 (MHOG), L39 (MNHOG), L40 (MHOG), L49 (MNHOG) and L50 (MHOG).  Perforation is 13.5 x 12.5.  Value of the stamps alone is $1635.00