The Ford Motorsport speedos are Factory catalog offers equivalent to the "certified calibration" speedometers used in the SSP...minus the actual certification that was likely provided
They follow the SSP offerings, in which 140MPH was offered for '87 thru early '89 and 160MPH was late '89 thrue 1993. I believe the 1989 SSP was a mid-year changover with early '89's getting the 140MPH certified speedo and late '89's getting the 160MPH. All 1990+ SSP's got the 160.
The Motorsport 140MPH speedo was sold in '87 thru the 1989 Ford Motorsport catalog. 160MPH was 1990-1993 catalog offering. I'm sure there was some overlap with the 1989 year . The catalog motorsport 160MPH speedo actually required the installer to trim a corner off (see below) for install in a 90-93 car.
The 140MPH unit was available in the Ford catalog for 1989 as the M-17255-F speedo. Starting in 1990, the 160MPH speedo was M-17255-J
Motorcraft speedo units:
87-89: 140mph E7ZM-17A277 - (
M-17255-F)
89-93 160mph E8ZM-17A277 - (
M-17255-J)
For SSP
87-early89: 140 mph E7ZV-17A277
Late 89 -93 : 160mph E9ZV-17A277
Any late 89 factory 140mph speedo is worth a premium, and those Motorsport and Certified Cal speedometers are a little rarer and fetch a premium.