Like everyone else following Main's advise, I found the job easy except...
I bought 3/16 packing and made up 3 rings using a 1" pipe and it turned out my set up used 1/4 packing and only 2 rings. Go figure:cussing: another trip to West Marine.
I found the toughest part on a MKIII was the stuffing box is directly under the cabinet face where it is virtually impossible to get 2 wrenches on it. I had to use a center punch and hammer to lightly tap the lock nut until it was freed enough to un-tighten by hand. I used PB Blaster for a few days before, just be careful not to get it on any rubber parts. I also used a stainless steel wire brush in a drill to clean the threads.
Good Luck
Bob