[68 TT]

The use of the two-piece may also have been to take some load off the transfer case tail housing and prevent tailshaft yoke pull-out under extreme suspension travel on 4x4 models. It may also have something to do with U-joint maximum angles being exceeded with the shorter driveshaft on the 4x4's too. All the 4x4's I have owned have been 2-piece and the 2wd's have all been one-piece. That doesn't mean jack as far as reality goes but it's a possibility

They made no sense as to when they put the larger diameter driveshafts in vs. the smaller ones either.

My 94 K2500 ECLB camper special had the same 454 and 4L80E as my 95 K3500 ECLB DRW truck also with the camper special option code but the 94 came with a 3-1/2" diameter 2-piece driveshaft and the dually came with only a 3" diameter version. The only real difference between the trucks besides the DRW was the 94 having 3.73 gears & NP241 and the 95 having 4.10's and the B-W transfer case that came in the 1-tons. You would think the DRW truck with its 1400 pound greater GVW would get a bigger diameter driveshaft but it didn't. Both had visible GM part number tags on them under the dirt leading me to believe they were original parts to the trucks and the fasteners looked like they had never been removed so they were probably not installed from another vehicle.

It turned out the rear section of the two-piece from the 94 K2500 was a perfect fit as a one-piece driveshaft for my 89 RCSB project truck when I built it with a 9.5" 14-bolt and used the medium length tailshaft T-400 that was in the 89 RCLB donor truck I got the cab from once I put the right transmission slip yoke on it to match the trans. Thanks GM, no custom length driveshaft required