Dead speedometer

Good day all I'm new here
So I have a question---I had the rear main seal changed on my 1999 Tacoma Pre-runner a couple weeks ago and now the speedometer doesn't work. NEVER had a problem b4 this. The mechanic said it was the drivers side. After that didn't work he is saying it must be the right side. Could it not be the cable? Because I've watched him put 2 different sensors on and nothing!
Can someone please help me?
Desperate seeking a working speedometer

 

I have similar problem on my 2001 Prerunner...no one seems to know,...! I have read all the forums...been to the dealer who told me that their diagnostics machine doesn't go back that far...I have replaced the speed sensor on the tranny,...swapped out instrument cluster...and now I am looking at the ECU. Seems to be a tough problem for the Type 1's...! Good luck...!