I was a little surprised that the splines go straight through and are open to the yoke. It's possible that a rubber baffle or something is missing. In any case it's important to keep the splines lubricated to keep contamination out. Turns out everything was well lubricated and the splines were in good shape. The out of phase shutter beat up the u-joints but didn't appear to damage anything else. I hope!
U-joints were about $75 each. $10 for a new spline seal. Could have been worse. Used Spicer series 1610 driveshafts run about $600 and you would probably have to have it shortened. New from Spartan are about $1200.