I currently run 35 with a 3" TERAFLEX AND 1 " MORE bL. It looks like I have plenty of room for 37s but i really want 40s anyone running something similar with 40s?? That 6" long arm just seems so far outa reach

 

Have you replaced all your control arms, brake lines, and trackbars? If you have, you could just put a spacer on top. I'm running a TF 4" with 2.5" spacer.

 

After you replace all the parts you need to, like in what ranwitscissorz said, you may be spending just as much as a 6" long arm kit which already includes all of that. I know Teraflex sells a long arm upgrade kit but its for their 4" kit. You may want to PM Joe from Teraflex to see what your options are.

For now though, I wouldn't suggest running a basic 3" lift + spacers + BL in order to run 40" tires.

Plus, do you have an X or Rubicon? 37" tires are prob the max you can go with Dana 30 axles which come with the X. 40" tires need alot stronger axles so if you have the Dana 44 Rubicon axles, you'll be ok there....for a while.

Good luck!