I looked for this for a long time and never found one, online or in junkyards. What ended up working for me was a 3/4-ton Suburban driveshaft. I think it was from a 91. They use a two piece and I just took it apart in the middle and used the section with the slip splines. I don't have my notes with me but it was about 33-34" cap to cap in the center of travel.
Anyway, you might find something like that because the 3/4-ton stuff uses 1350 U-joints and is much easier to find.