2005 F-150 FX4 6in fabtech 5.4L, no body lift, 35 in tires, i get a clunking in
4WD when I turn, are the cv's going bad?

 

Same happens to me. When I turn in 4x4, my front end pops but only in 4x4. I have a 2006 with 6" Fabtech and 35x12.50s. I also had 4.56 gears put in about 25,000 miles ago at the same time I lifted it. And I did change the diff fluid after the 500 mile break in period for the new gears. I also broke the end bolt off one cv axle when putting the lift on so I have one original cv and one with about 25,000 miles on it

 

Probably, look at the boots one may be damaged.

 

Boots are fine, any other sugg?