The running hardware should be installed just before painting the color coats on your boat. This will keep everything out of the way until the last.  There are so many different combinations of motors, propellers and rudders made by different companies it's impossible to cover them all.  To keep everything on equal ground, I will keep with Dumas and talk you through using their running hardware kit.

The Running Hardware kit #2341is the twin screw, twin rudder running hardware kit for two 6 volt motors.  My kit was complete.  Here is the contents:

2 Drive shafts
2 Stuffing boxes (with oilite bearings)
2 Rudder assembly
1 Rudder arm (metal, for 1/8" shaft)
1 Double rudder arm
2 Strut assemblies
2 Brass Drive dogs
2  Set collars
2  Thrust washers
1  Propeller, right bronze, 2" diameter
1  Propeller, left bronze, 2" diameter
Screws, nuts, bolts and washers for assembly Instructions for assembly.

  

The kit includes instructions for the alignment and installation of the rudders, struts and stuffing boxes.  The same instructions are included in the USS Crockett kit.   There is no mention of filling the stuffing boxes with grease.  I used a full synthetic white marine grade grease.   This is much easier to clean up than the automotive grease you would use to pack wheel bearings. 

The bearings in the stuffing boxes are milled to close tolerances, demanding adequate time to properly align the struts.   The first night I could not get the alignment to my satisfaction. I put the Crockett aside to try another day.  The next day, I was able to get the alignment of the shafts and struts the first try. When aligned, the shafts will turn with very little effort.  Because of the close tolerance, any slight misalignment will cause the shaft to bind.  And I mean any slight movement. If you do not take your time, you will cause the motors to work harder causing shorter battery run time.

The struts attach to the outside of the hull with four small bolts and nuts.  If you are building a scale model, you may want to add a little filler around the base of the struts.  This will blend them into the hull.  They will look built into the hull instead of just  looking "bolted on".   As for the rudders, the modeler must trim them down to 2".   These were cut very easily with a razor saw.  They contained mold markings and flash.   The rudders did clean up nicely but did required some filler.