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 pre-77 rubber bumper car (OD and non-OD were the same) - SN5230/13 1000tpm now immediately above the rim:

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 - SN-5230/14 and 620 turns per kilometre again just above the rim:

RHD 77-78 4-cylinder plastic dash with markings each 10mph SN5234/00 1000tpm:

RHD 78 and later 4-cylinder plastic dash with markings at odd mph only SN5234/02 1000tpm:

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: