Original sentence: Around this time, an 'MM' service had been proposed, which would have run through the Chrystie Street Connection 57th Street via the IND Sixth Avenue Line, but this never materialized.It was included on some rollsigns printed at the time.MJ was only marked on maps and station signs; the cars along that route never had signed designations.On July 1, 1968, M service was extended two stations in Manhattan to end at Broad Street.Since the new cars using the new letter designations were not yet running on the Myrtle-Chambers line, it remained designated as 10; while M was used to designate rush hour Nassau Street specials on the Brighton and Fourth Avenue Lines.The west half of the BMT Myrtle Avenue Line was closed on October 3, 1969, ending MJ service, and  shuttle service was begun east of Myrtle Avenue/Broadway.With the opening of the Chrystie Street COnnection on November 26, 1967, the new letters officially redesignated the 10 and 11 services on maps and signs
Edited sentence: (It was included on some replacement signs printed at the time).26th 1967, was the day the letters officially redesignated the 10 and 11 lines.Around this time, an 'MM' service had been proposed, which would have run, probably middays (when the K] service didn't run), through the Chrystie St.July 1, 1968, M service was extended two stations in Manhattan to end at Broad Street.Since the new cars using the new letter designations were not yet running on the Myrtle Chambers line; it remained designated as "10"; while "M" was used to designate rush hour Nassau St.The MJ was only marked on maps and station signs; the cars along that route had never had signed designations.This would have been useful, and the neigborhoods served by this portion of the 'M', such as Ridgewood, Queens, have no direct access to Midtown Manhattan.What was even worse, the west half of the BMT Myrtle Avenue Line was closed on October 3, 1969, ending MJ service, and  shuttle service was begun east of Myrtle Avenue/Broadway.connection to the 6th Avenue line's 57th Street terminus, but this never materialized.specials on the Brighton and 4th Avenue lines