Hi everyone and thanks for reading.

I just finished swapping a 4.3 to 5.3. The truck is a 2007 classic body WT single cab with nv3500 transmission. The donor 5.3 is from a 2004 yukon xl.

It all went somewhat smooth with the guide I found on this website but I have ran across an issue that even my local shop cant figure out.

I had the local shop change the vin with HP tuners and delete the VAT system and change the program to manual transmission.

What I am running into is the RPM reading is about 1000-2000 off depending on if its at idle or driving.

With this also my speedometer is way off. It reads 0 when we are not moving but at 20 MPH its reading 45-50 and 60 MPH its reading 120 ( pegged).

I had to remove the fuse for ABS because it would think I was sliding from the wrong speed readout and I could not stop easy.

If anyone could help me run this down that would be awesome. My local town just does not have a lot of help in this.

Thanks everyone.