Was that 2-3 above or below actual?

In almost the same boat you are going to 4.10 w/29.5" tire

 

Ditto

 

Sorry, I don't recall, the gear swap was in 99'! If you are within 2-3 mph either way, above or below actual, I would say you're doing good. No? A tire size decrease or increase if .5" in diameter could be about that much......

With your 4.10 w/29.5" tire you have to go with a 23 tooth gear, as far as I know there is no other option available other than custom tuning.

 

Sounds good thanks just tryin to avoid any...unwanted attention

 

Just a bump for an old thread. FYI with stock tire size and 3.55s going to 4.10s the speedo will read 2-3 OVER actual with a 23 tooth VSS gear. Just did this swap and although the difference was not dramatic it was definitely noticeable. MPGs dropped by 1 with alot of mixed city/hwy driving.

 

2 to 3 over is probably close to right on for the ECM. Ford sets the speedo to read a bit high on purpose. Check the odometer against highway mileposts or a GPS, it's probably very close to exact.