Call Jim at PATC Transmission (888)877-1008. He will want you to drive your truck, while use a GPS type device to determine actual speeds, make note of what your truck's speedo is reading when you are actually cruising at I think 30, 40 & 50mph. I also went with 3.55 in my truck and found that I was about 20% slow. I bought a in stock 19% speedup ratio adapter from him for $62+postage. Now it reads dead on.
Craig
My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear
My truck ....... Respect The Rust
If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.
