Speedo Reference Numbers and Turns per Mile

An SN6144/00 1040tpm for a UK Mk1 3-synch non-OD car - reference number and tpms immediately below the odometer. An OD car would have an SN6144/01 1020tpm. However Jaeger speedos seem to be 20tpm higher i.e. 1060 and 1040 respectively.

An SN6144/23A 1280tpm for a Mk2 68-73 UK 4-synch OD chrome bumper car - again reference number and tpms immediately below the odometer. Oddly although the TPMs were the same OD and non-OD speedos have different reference numbers. The non-OD equivalent for this would be SN6144/20.

1974 model year cars have a BS suffix to the reference number but are otherwise interchangeable in both directions with the earlier Mk2 speedos.

A 1000tpm as would be fitted to a UK rubber bumper car (OD and non-OD were the same) - reference number and tpms immediately below the odometer as before. However this particular reference number is not applicable to the MGB, but is from a Midget/Sprite.

An 80mm KPH speedo as fitted to 4-cylinder cars from September 74 to June 76, i.e. rubber bumper cars prior to the plastic dash. Not the clearest picture, but it is just possible to read the reference number as SN-5230/14 and 620 turns per kilometre.

A 960tpm from a factory V8 - reference number and tpms immediately above the lower rim. The same speedo was used throughout i.e. both chrome bumper and rubber bumper. Later plastic-bezel gauges (4-cylinder cars) had the numbers in the same place.