I believe my 02 Ram 1500 Rear diff is 3.92? I knpw for sure its open diff i verified. Would it be easier to buy a $600 axle assembly or $300 sure-grip lsd converter? And if i did buy the full axle can i jus drop n swap or do i have to adjust backlash still?

 

You can swap an entire end to end axle, no adjustment needed. You need to check to see if your spring clips are going, you may be on borrowed time if it's the original rear and/or hasn't been looked at or repaired.