variable number - Boeing 747 | information center

Boeing Variable number

example:

PH-CKA B-747-406ER/F 33694 / 1326  RL681 R7166

This number indicates  specific airframe, including all options selected by an individual customer. Mostly a number-block is reserved for expected additional orders by the same customer. The larger the customer the more numbers are blocked in advance. If the block is full (more aircraft ordered , than initially expected), a second block is used.
First letter gives the aircraft type:

P =   737, Y = 737NG, R = 747, N = 757, V = 767, W = 777, Z = 787.

The second letter stands for the sub-model or a further sub-division . This is the variable (effectivity) block and the three following numbers are the sequence within the block. Note that not all numbers within a variable block actually get built.

Examples :
RA001 the first built 747-121 for Boeing.
RA002 and further is used to identify the Pan Am configuration (airline specific options)

For the 747-8:
RC001 till/incl. RC020 = reserved for the 747-8 intercontinental BBJ customers
RC021 and further (end number not specified yet) for DLH
RC501 till/incl. RC520 = reserved for Cargolux 747-8F freighters.

Here you may download all the 747 variable numbers in a Word Document. This is credited to Peter Evers and Ronald Aker who collected with great enthusiasm. Thank you!