Ok so first off my head hurts from thinking about all of this.
Here's my deal, I got a 3" PA body lift for nothing through a guy i work with, on top of that I have sitting at home my new Ford torsion bar keys and a 2.5" add-a-leaf for the rear of the truck. From what i've been able to come across so far it looks like there might be a chance I could squeeze a 35" tire under there if not a 33" should fit without many issues.

So my next question is what kinda backspacing do I need to run.
I'd like to run an 8" wide wheel but it looks like for the 35" i'm going to have to run with a 10" wide. As for the backspacing what about any offset? I know most lift kit manf. recommend a 4.5" backspacing, would that work with both the 8" wide & 10" wide wheel?

 

BTW - what is our stock wheel backspacing & offset for the 16x7 wheels

 

idk about back spacing but a 33 will fit with crankin tbars and thats it

you might fit a 35 but it would be close

 

Offset is 31mm (5.22" backspace)

 

Now when you say a 33" with cranking the t-bars, are you talking about with the 3" body lift & bars cranked?
I've heard with the Ford keys and add-a-leafs I can pull out over 2" of lift that on top of the 3" body and i'd be in the 5" range with 6" fitting 35's, although i'm not sure how tight a 35" fits with the 6" lifts.

 

now i may be mistaken on the 1500s but tbars ONLY can fit 33s

i know for a fact that on a 2500hd you can fit 285/75r16s(almost 33s) with no tbar cranking and no rubbing but then again the 2500hds sit about 2" higher than a 1500 i think

 

dude i would strongly advise not doing the tkeys. i had the exact same lift you were talkin bout but now im just down to the 3" body and im runnin 33s. i dont think i coulda fit 35s though when i had the 3" body and the tkeys adn the add-a-leaf

 

3" body no tkeys and a 1" add-a-leaf