E38 - t43 - speedometer error

I could use a sanity check here...

I have a customer with a 2009 GM 1500. He installed a lift kit with 35" tires and 4.56 gears.
I have tried to adjust the speedometer being 6mph off and I have had zero luck with getting it to work properly.

In the Speedometer on the E38 I used the Speedo Calculator (like I've always done in the past) and it made adjustments to H0136 and H0139

I then went into the T43 file and adjust the tables that have the same numbers. Basically, making sure everything matches.
I then went into the "Ratios" folder and put in that it has 4.56.

With that said, the truck is still 6 mph off. Which gives us an issue with trans shifting.

Any help would be appreciated.

Attachment 22857Attachment 22858

The speedo adjustment tool has a means of entering a % correction... have you tried that...?