FL Columbia Speedo Off 3-5MPH

As title states. I've only had this truck for about a month and I knew something was fishy when my cruise was set at 65 and Werners were passing me left and right. I went by a few of those radar things that tell you your speed and at 65 it said 61-62. So I did some math and on the way back with cruise set at 1400RPM which should be around 65 it said 65-66 and showed about 70. The guys at FL are telling me that there is a 3% error cushion and that this is not out of that %.

Now I haven't been driving for 30 years or anything, but in my nearly 9 years driving, and driving some pretty crappy trucks, I've never had one this far off.

 

It's an 03.

Honestly when I got the truck, the ECM stated that the final drive was .73, when in fact it's .85. I had it checked out by the dealer and the tech all but argued with me over the final drive of the tranny. I don't have the typical rtloc 16909a converted to rtlo 16913a I have the rtlc 16609e converted to rtlo 16613b.

Now when he went into the ECM and changed the final drive, I remember his disconnecting the plug when it was asking him, "are you sure you want to save changed data?" I told the service manager that, but he seems to think that there's no way that could've happened. I just don't want to take it to another dealer and pay 100.00 for them to tell me what I already know.

 

Yeah my VW does the same thing except the miles aren't off. The speedometer and odometer get the same signal, just interpret it differently. There are TSB's for it, but doesn't correct it completely.