speedo gear

[ensmyers]

I just installed dual T-cases with a 93 in the front and an 81 in the rear.  The elecric speedo sender bolted right up to the 81 case, but the speedo is now way off.  Do I have to pull the rear off the 81 case and install the speedo drive gear from the 93?  Is there an easier way?  Unfortunately I did not save mechanical speedo sender that I pulled out.