Single or Double Cardon CV drive shaft.

Decided to go with the drive shaft replacement in hopes of alleviating the vibrations I have recently encountered after completing my lift.

Spoke with Josh over at Tom Woods and he tells me money back if they don't work to my liking.

So, question I have is whether to go with the single or double cardon shaft?

Also plan on adding some 2 degree shims under leafs above axle.

Lift I have is 3 inch total, so about 1 - 1.5 in the back.

Thanks!