I had the opposite happen. The speedo needle on my '54 would frequently fluctuate back and forth in a 20-30 mph range. I had a Patrick's 3:55 kit installed this week, along with the speedo gear set that he sells, and now the speedometer is spot-on and very stable. I had my wife pace me on the interstate yesterday and the 54 showed the identical speed as my 07, right up to 75 mph. (The 3:55 made a HUGE difference in the truck, as it will easily cruise at highway speeds, and the engine noise was noticeably reduced.)
