I have a Mark Williams billet steel 1350 trans slip yoke and a billet 1350 yoke on the rear from Moser. I had a local big truck driveline shop make me a 3" diameter steel driveshaft w/ what they call their "thickwall" tubing which I believe is .090" thick. Also using Spicer 1350 U joints.
It's been fine for a long time, but I don't race nearly as much as I used to. It's made plenty of deep 5 sec 1/8 mile passes, 8 sec 1/4s at nearly 3900 lbs.