Classic/Antique Car Repair: Spedometer drive for 52 Chrysler Fluid Drive, rear axle ratio, speedometer drive

Question
Is the spedometer cable driven off the transmission on a '52 Chrysler New Yorker with Fluid Drive? If so, can the drive gear ratio be changed(without removing the transmission) to correct the spedometer reading?  The spedometer reads about 15 MPH slower than the car's actual speed.I would like to correct it at the transmission end rather than at the speedometer end. Thanks for any help or advise.

Answer
Yes, the speedometer drive gear is in the rear housing of the transmission.   If you change the drive gear, you will also probably have to change the worm on the tail shaft of the transmission (the book will tell you which worm gear goes with which drive gear).   However, if this problem has not been caused by a major change in rear end ratio, there is probably serious trouble in the speedometer instrument itself.   If the odometer reads normally, (withing a few % of correct) yet the speed indication is this far off, you need to pull the speedometer out and take it to a rebuilder.

If the odometer is also 15% low, then your problem is in the drive gears - maybe someone made a major change in the rear axle ratio without changing the speedometer drive gears.

Dick