Kane,
I wondered about this too since the couplers on mine stayed perfectly lined up. I think that they must mate up somehow to keep aligned. I did not remove the coupler bolts, just loosened them, so maybe that is what kept them in alignment.
Also, after I got the gap to within .002" on one side of the coupler and zero gap on the other side, I loosened the rear pins and one of the front pins to try and get the gap perfectly even. After doing that, I suddenly had gaps of .016" to .019" at different points around the coupler. What happened is when I loosened the pins, the whole engine must have slid forward a tad creating the large gaps. So I just moved the engine to starboard to even out the gaps so that it didn't vary more than .002" from any two points on the coupler. I then tightened all the trunnion pins and checked the gap again before tightening the coupler bolts and they were all betwen .004" and .007". I got tired of messing with it at the point and tightened all the coupler bolts and torqued them to spec.
I will keep an eye out on the shaft packing nut (I changed the packing rope again while I was in there) and see if starts leaking water in a steady stream, I may have to go in and close the gap a little tighter.
Al
Al
2006 Mobius LSV