Power Derate in 4LO

[496Cubes]

I read over on the Diesel Page that trucks with the 6-speed have a derate in 4-Lo to protect the drivetrain. Is this true? Is it only for the Duramax or does it also apply to the 8.1 engine?

[Shaners]

I don't know if it is true or not, but if it is, I would guess that Lyndon Wester probably helped you out when he modified your PCM!!!

[1BADHD]

Its not true in the 6.0! I hit my 6000 rpm rev limit while sled pulling......if it pulled timing it wouldnt have made it that far.