Have a 2012 2 dr jk and was told if I run 37s on a 3 inch lift or anything bigger than a 3 inch lift I would need longer driveshafts...any suggestions or if I would need to

 

There are several threads on this. They are many manufacturers out there, J.E. Reel, Coast, Tom Woods, just make sure you are getting high quality spicer u-joints and not chinese made imitations. Alot of threads about how good they hold up as well...

 

You will need to upgrade the front driveshaft. Eventually you will need to upgrade the rear on the two door. i would suggest doing it sooner than later if you plan on wheeling it. JE Reel makes good shafts and uses good joints.