Model code consists of 2 letters followed by 2 or later 3 numbers.

example: Celica Supra's model code is MA61

the first letter means that this model has a M-series engine, in this
cas a 5M-GE

the second letter relates to the chassis family, other vehicles that
have an A-type chassis are RWD Carinas and Celicas.

	F	Celsior (Lexus LS)
	S	Crown, Aristo (Lexus GS)
	X	Cressida, Mark II, Chaser, Cresta
  	Z	Soarer (Lexus SC)
	A	RWD Carina Celica, Celica Supra, Supra
	V	Camry, Vista, (Lexus ES)
	T	Corona, FWD/4WD Celica, FWD Carina
	W	MR2
	E	Corolla
	P	Starlet
	L	Tercel

	J	Land Cruiser

the first (+second, if a total of 3) number stands for the model revision,
in this case 6, for Celica Supras produced 1982-1986. Similarily, Carinas
and Celicas produced 1982-1985 are of revision 6. Mk1 MR2's are of 
revision 1, Mk2's of revision 2.

the last number will specify more accurately the options level and
exact engine type.