After the 7/8"-18 NPT fitting boo-boo - I realized that the threads were a standard 3/4" NPT which made sourcing the parts a lot simpler. Since I already had a number of 1/2" NPT nipples of varying lengths I elected to get the following items for this little upgrade:
a 3/4" x 1/2" NPT Reducer Bushing
and a 3/4" x 1/2" NPT Reducing Elbow
as that would be the cheapest avenue for me.
I added a Hex Head Plug, 3/4 In, Threaded, Blk Steel
I was all set. I used a 1/2" x 4" NPT nipple
to get the elbow out past the Rear Rock shaft Rod. After assembly this is what I have:

Now I can top off or re-fill the reservoir without using a funnel and without spilling a drop


