How old is your battery?
Have you had the starter itself checked or checked the connections to the starter?
There is a engine to chassis ground down on the drivers side near the area you think that sound came from. Take a look. If it is highly corroded I recommend running the new chassis ground that many others have ran on this forum. Just search chassis ground.
Let us know the answers to the above questions and that gets us a step closer.
https://www.crossfireforum.org/forum...le-engine.html
Above is the link to the additional chassis ground i spoke of.