Did you change to the 1954 3.90 Ring & Pinion or to a 3.55 Ring & Pinion?
The speedometer gear set changed in 1954 because the rear-end changed from 4.11 (47-53) to 3.90 (1954/55st).
If you have a replacement 3.55 R&P, your speedometer will still be off with a 1954 3100 speedometer gear set.
