Speedometer question

[Johnnyhotrod]

I only see 2 possible answers, 1) the original meter would also be +5 if it was in good working order or 2) the 2nd meter has something wrong with it causing it to read +5. One of the things you can do when troubleshooting is "insert known good part". Neither of your meters seem to fit the bill. You can try and confirm your reading with yet another "known good" meter to see if it matches or you can just go with it and tune the trans gears to correct the +5...