[TA455HO]

Originally Posted by eaglesan13

On a related topic, why do some cars have a speedo cable adapter while others don't? This is a picture of my 70 Formula, (with the original trans) and it has the adapter. I have seen this on some other 70's also. My car came with an M20 with a 3.55 posi.

The speedometer heads were calibrated for a specific tire size, transmission and rear end ratio. If parameters start to fall outside of the values used for the calibration then an adpater is commonly used if the speedo driven gear can't be changed enough to get an accurate final reading.

In 1970 there were 4 combinations that used an adapter and 12 combinations that did not.

In 1971 speedo cable routing was carryover. The number of cables was reduced by one due to the elimination of the adapters on automatic transmissions. The only adapter used was the Right Angle Adapter 6477964 used on the R.H. side of the manual transmissions, but not with a 455 engine.

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