They are a fairly common size, all a good driveshaft shop would need to do is take measurements and use a similar U-Joint with the same dimensions.
I am having a custom rear driveshaft built right now. There will be a u-joint and CV joint on it.
I wonder if the front joint is from the Oldsmobile bravada? I think it used this BW case first. I had to use a trooper front joint when I ditched the tod case.