Tips:
Don't do it. Use an LML. Just do a CP4 swap first and be happy.
I will probably never be able to push all the air the L5P can handle because of the turbo configuration. My desire to go with the super strong and more potent new configuration cost me more than you could set up an earlier one and get more power. I kept the catalytic converter, etc.
A 3" body lift is an absolute must as the L5P is more than 3" taller than previous gens.
I did not personally do 90% the work, but spent a $H_T ton. I still have a lot of work left to do.
Used a custom built NP205 with twin sticks behind the Allison. The Allison output changed in 2017 too and caused extra pain and expense. Stuck with the 2:1 low range as I don't do rockcrawling.
ORD front springs and crossover, w/ 2wd steering box from ORD. ORD Shackle flip rear.
I'm paranoid for good reason (Diesel Brothers?), so I will be circumspect about what all I share. It is running the factory ECU.
Keeping the 4:56 gears as when I put 37's on it that will be ideal in 6th gear. Detroit Locker in the rear from factory, open front. Wish it had a geared torsion LSD, but maybe someday.
Vintage Air using the new compressor.
Truck has 59k miles, drivetrain has 17k from a rolled 2017. 2 years in progress to date.