I am trying to find a fuse to tap to run a led light accessory I only want to have power when the Diesel is on.

The standard (Gas) user guide has fuses in the engine compartment on page 334/335:

The Diesel supplemental guide has a fuse block in the engine compartment on page 50/51.

I think what is making this tricky is I have the Diesel Duramax so my fuses are different. It doesn't have the ignition fuse based on the supplemental guide. Am I wrong?

What do you think I can tap into that is only powered when the Diesel is running?

 

Test light and probing. I had to run a wire from underhood fuse box and use a fuse tap to get a ignition switched source for my radar detector in my '11.