I have 4.10s and had the thrumming with stock tires/coils. Put the 315s and TRex/KORE coils on and thrumming has evolved into a shimmy at the same rpm/speed.

 

I have 3.73s and mine starts the vibe at around 68mph. I can put it in neutral and coast at that speed and still vibe, so it's not an engine RPM vibe.

Dumb question . . . Is the front diff the same regardless of ratio (3.73 vs. 4.10)? Whenever I read about changing ratios, only the rear diff is discussed. I makes sense that both would have to match in a 4x4.

Neil

 

the front diff ratio must match the rear diff ratio. It would work until you engaged 4WD. Then all hell would break loose