I will add some information here.

Seatbelt pretensioners changed from red connector one to yellow connector one with MG TF serial number 4D 620549. That is the serial number from which alarm system changed from Lucas to Pektron. That is because how Lucas and Pektron system receive information about if or not seatbelt is buckled-up or not in order to lit dash light.

Airbag ECU changed from RC5/EC5 model to AB Autoliv model with MG TF serial number 5D 639631. That means yellow connector seatbelt pretensioners worked on both systems: RC5/EC5 and AB Autoliv. 

Having this in mind change of pretensioners might work for part of airbag ECU but will not work for part regarding seatbelt warning light on dash.

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