Which speedo drive gear 7 tooth or 6

[Bolt on 5.0]

I have a 91 mustang gt the car has 4.10s the speedo is off to much and is very anoying. I called over at 50resto and they said I need the 7 tooth, but want to make sure. I was searching on this site and seems others with the same trans 1990 and up are using the 6 tooth. Anyone positive on this, I will be ordering this week both drive gear and speedo gear

 

[Roland69]

Do a search on speedo gear there are a tonne of theese posts and most have the chart you need to look at.