What's the difference between a "dual drilled flywheel" and a "6 speed flywheel?" I see both wording used to describe the flywheel that comes with various 13" conversion clutch kits for the NV4500. Are there any advantages or disadvantages to using one or the other? Thanks!

 

I think I figured it out. The dual drilled flywheel is a stock nv4500 flywheel (I believe used in years 94 to 2000? 5 speeds) that's drilled to accept both 12 1/4" and 13" clutches. The 6 speed flywheel is strictly drilled to accept 13" clutches and the ring gear is located differently causing the need for the starter spacer.

So, now the question I have is...if your trucks' nv4500 already has a dual drilled flywheel 13" conversion clutch and needs a new clutch, but not the flywheel, from what year would you select to find the clutch to order?

 

Ask the clutch builder/supplier.