Yeah I''m the one that did it.
The driveshaft pushes into the carrier bearing at lift, because the 4-link pulls the axle forward. It gets a lot of lift. I got about a foot out of it on the 90 PSI my shop compressor puts out.
Theoretically it should get another 4-6 inches. Because the driveline is so short, and its set up for so much lift, and the 4 link is shorter than it could have been (it was pre-ordered) it happens to push the driveline in. My truck is about the same wheelbase and has a one piece driveshaft, and I love it. And my truck has a much larger wheel arc than Manny's truck does. Because my 3 link is shorter than his. I think with a 1-piece driveline, the travel would not affect it as much.
Manny, theres a good driveline shop out here about 8 miles from my house that will do it. When you come back for the bodydrop, we can possibly do it then. I'll be cutting the cab so modifying the rear tunnel won't be a big deal. Then all I have to do is modify the crossmember where the carrier bearing mounts. Its up to you though. People have mixed opinions on this. I never liked the 2 piece drivelines for a lot of travel. They seem to work fine if you get less than 8 inches of lift though.