Betwenn 1967 and 1968 around 5.000 GTs were built. They were the only Amazons that still had the B18 in these years, all other Amazons already had the B20.
You should be able to identify the car with the type number and the production number.
The type number should read as follows:
133x51M, which stands for:
13 = Model 130 (2door)
3 = B18B engine
x = this number indicates the destination market
5 = gearbox (4 gear plus overdrive)
1 = left hand drive
M = Year 1967
The production numbe should be between 216950 (first number for 130-model in 1967) and 279900 (first number for 130-model in 1968).
You can look it all up at