Speedo gear change

[Boostin TA]

Hey Guys I am finally going to change out the drive gear for my spedo so I can actually tell how fast I am going now with my new rear end. My question is where is the gear located at exactly? Do I have to remove the tailshaft housing? Will I have to drain the trans fluid? Ive tried looking in all data and mitchell on demand but neither one have a step by step R&R procedure.

 

[SSedan64]

The Driven gear is on the end of the speedo shaft on the side. The Drive gear is on the Governor shaft inside the pan.