speedo reading high

bought this jeep a year ago with sye kit already installed (still has vibes and im not sure if its ever been greased but not the topic at hand) . Im running 33 inch tires and at 65-70 mph im running 2500 rpms and my speedo is reading at 100mph. seems to have aftermarket speedo sensor setup running from the sye kit. Anyone know how to sort this, i plan on re gearing to 4.10 by installing a 4 cyl front dana 30 and an explorer 8.8 at some point but it seems the gearing is already not the stock 3.07s using an calculator it says im roughly geared 3.73 . any idea how to get the speedo corrected. its a 1995 yj 6 cyl lifted by old owner who said its 6 inches but i never measured…

Sounds like you just need to replace the speedo gear to the correct teeth count based on the chart in the link.

midwestjeepwillys.com/speedometer-gears.html

hope its not one of those magnetic ones ive seen in some. Do i have to take transfercase out to change speedo gear?

Its all mechanical. No, just look for the one wire/cable that goes into the transfer case and is held in place with one bolt. Remove the bolt and it may take a little effort to pop the unit out. then just pull the old gear our and pop in the new one.

thanks dont know why ive let it be for so long, id probably have way less miles on my speedo

I have the correct gear installed based on my gearing but the speedo is still running really high. do i have a bad sensor or should i try lowering my teeth count. its running about 15 - 20 mph off at 65 mph at 31 teeth , sitting on 33s geared 3.73

or could it be a failing sensor?