Leroy - where you been!?
Two options to correct speedo deviation when you change rear gears:
1)You can order a ratio adapter from a speedo shop (nearly all offer this) which is a gear set that will go in between the speedo and the tranny - usually on the tranny but it can go on the speedo head too
2) Pull the speedo and send it to a qualified shop for calibration based on your setup.
I chose the latter and sent my speedo to Scot Speedometer in Pontiac, MI where they dialed it in for the 4.10 rear gear swap I did on my 8 lugger. Now I'm installing an A833 OD and I am going to use option 1 for a ratio adapter because I can't stand the thought of another contortionist day under the dash of the '51 pulling the speedo AGAIN!
