orientation depends on the , "arrows" on the edge which are supposed to be toward a flange.
I only see one of the arrows in your picture and it looks like you need to turn or clock it one hole over. (Less noise.) Nuts all go on the flange side and need spring washers or a drop of loctite blue for safety.( Saw the one, not the others.)
Yes, the center bearing mounts from under.
A suggestion would be to check for alighnment on the shaft horizontally and vertical. String and a measuring tape, magnetic angle protractor, homemade wooden jig, etc. keeping in mind the two shafts are different diameter.
Guibo history trivia- there are two. One has the standard 10mm but there is an earlier version with 8mm for ZF/ automatics. Don't mix up the two and something to check when using an auto driveshaft on a 5 speed conversion if the driveshaft shop didn't catch it. Walloth still sells the smaller one.
P.S. Preload the bearing about a 1/4" forward before tightening.
