Thats what I thought, but there are three different injector types for the 300 tdi.
Injector - 300TDI - manufactured by Bosch - DISCOVERY 1
ERR3339
£34.00 ex VAT
Injector - 300TDI with EDC (requires 1) - DISCOVERY 1
ERR3337
£129.00 ex VAT
Injector - 300TDI with EDC (requires 3) - DISCOVERY 1
ERR3348
Its the £129 one that has the sensor on, but the other three (ERR3348) are not the same as the standard (ERR3339) parts.