The Stovebolt Site Forums The Shop Area The HiPo Shop Speedo Adapter or Speedo Gear?

I can't answer your question. I have used both in different trucks. What transmission are you using? sm420? It might make a difference.

I callibrated the speedo on my 59 gmc by changing the speedo gear and using charts. However I am using a Dodge transmission, so I had to use the dodge speedo pinion. Your experience will likely differ from mine.