[Does anyone out there besides me remember when MSBA had the 8 1/2 foot wide 1975 Flxibles from the city?]
There were a number of occasions on which new look buses from NYCTA or MABSTOA finished their lives as MSBA buses:
571-580 were originally TA 5301's in the 1001-1130 series.
500-506 were originally MABSTOA 5303's in the 6401-6699 series.
507-511 were originally MABSTOA Flxibles in the 4600's
350-399 were originally Flxibles in both lower and upper 7000 series. These 50 buses came when MSBA was really having a major equipment problem.