Speedo drive gear

[ensmyers]

Help.  I installed dual T-cases and moved my speedo pickup to the rear case and now my speedo is way off.  I have an electric pickup on a 93 truck, and stuck it in the rear 81 T-case.  I need to know tooth count on both the metal drive gear in the T-case, and the plastic drive gear on the pickup.  I am hoping to be able to just change out the plastic gear on the pickup and avoid tearing apart the rear case.  Unfortunately, I no longer have the mechanical pickup from the 81 case to compare.  Any info would be helpfull.