In March of 2003, MacGregor introduced the all new MacGregor 26M, to replace the 26X that had been in production for 7 years. Approximately 5000 of the X had been produced before being replaced by the M. I have a 2003 M with this number
MACM0047E303
MACM = manufacturer and design, MACM = 26M
hull = the serial number of the hull, runs continuously for a given design.
E3 = assembly date; A thru L = assembly month; single digit = calendar year.
03 = "model year" begins on July 1 each year and continue thru the following June 30 (except I believe for 2003 for obvious reasons).

Hence mine, MACM0047E303, a MacGregor 26M hull number 0047 built in May 2003 to model year 2003 specs.
Duanne Dun posted this a while back.
Q1