Have gotten my truck running with the 6.5 swapped in. I have a rattle at the top of each gear that I don't hear in my suburban with a factory 6.2. Truck seems to have good power. I retarded the timing from line to line some. Picked up some temp in water according to the gauge. Still have the rattle noise. Should I try to advance it some or set it back line to line? Anyone have any other ideas?

A scanner that displays timing would be ideal to set the timing where you'd like it in the range.

Otherwise, just try and keep it in the middle or slightly to the right, 2.5mm no more.