I ran into this problem when I did my lift install a while back. I have the exact answer you need. When lifting your 6.2SD more than 2.5", you need to have someone make you a custom 2" OD drive shaft. I had the lift installer remove my driveshaft and send it to a fabricator, so exact measurements could be taken. It took the entire day, but I had the lift, new drive shaft, and tires installed. For a completely new drive shaft, it was $450.

I would suggest having a completely new shaft make, instead of using parts from the existing, so if you even want/need to bring the truck back to 100% stock, you can easily swap them out. See the pictures I posted in the thread linked below, discussing this topic. I hope this helps.

https://www.ford-trucks.com/forums/1...-wheels-2.html