Right... so... 8 months later I have finally resolved this issue.

Over the last few months the symptoms were getting progressively worse in terms that it would sometimes take numerous attempts trying to start - only to get a "one click" each try. Finally, when it got so bad that I was spending 2-3 minutes every time I wanted to take my truck anywhere just trying to start it, I decided to pull the starter and test it.

Pulled the starter, took it to the Autozone for a bench test, it passed... I didn't believe it as it sounded kind of weak during the test so I bought another starter, put that in and the issue has completely been resolved!

So for those of you experiencing "one click" when turning ignition, check your cables and if that's not the cause, you will probably need to replace the starter... even if it appears to be in good working order.

QUICK NOTE .................................................. ....................................
This is not the first time that a starter failed even though it passed a bench test. I remember working on a 98 Ford e150 where the starter would be cranking slowly, with the fresh battery and good cable connections all the way down the line. The issue was completely resolved after replacing the starter, which also passed the bench by the way.