The 8 designation was brought back for the only remaining IRT elevated service, the IRT Third Avenue Line in the Bronx but trains never displayed the number. When the Lo-V cars (which did not have front signs) were replaced by R12 cars the front roll signs in use did not contain the number 8 and instead displayed the word "shuttle". For map and sign purposes MJ was assigned to the last old-style elevated line, standing for "Myrtle Avenue Line to Jay Street", while the "Myrtle Avenue line to Chambers St." subway service would finally receive its M designation. The short-lived new Sea Beach Line super-express service was made NX. The Q, QT and T disappeared when the Chrystie Street Connection opened; thus they never had colors (until after the elimination of double letters, when the Q came back; by that time the current color system was in place). By 1968, all shuttles ("SS") were green. For a short time, the off-hour shuttle between Metropolitan Avenue and Myrtle Avenue was added in 1969 when the MJ service to Jay St. was discontinued, and that part of the line abandoned. The shuttle was soon renamed "M", however, as it only ran when the M didn't run to Manhattan.