You can easily get enough lift to run a 33 ish by just changing out your torsion bar levers/keys in the front and by adding a small block in the rear. Contact Quigley for your build sheet and ask them the GM part number for the front levers/keys. I posted the info in my thread when I did it. I can look it up if you cant find it. I would suggest though if you’re willing to spend a little, going to custom rear leaf pack as Marret suggested from Weldtec. You can also go whole hog and get the full front lift kit as well.
2015 Chevy Express 3500 Duramax
w/ Quigley 4x4 & Agile Fox shocks
Sold 2005 E350 Chateau
Quigley with Agile RIP, 6.0 PSD