84 B Starting Issue

Wow, truck was starting and running fine, then all of a sudden this morning I put the key in, the dash lights up, and ruuur, ruuur, click. Then after, turn the key and click, click, ruuur, then the dash lights turn off for about 10 seconds, then turn back on. I put a floor charger on it with fast charge, thinking it was battery, and the same thing happens. What the foook is going on??? Well I took the starter off and taking it in to get tested, hoping that's the problem Oh and to top it off I turned on my turn signal by accident and there is a funny noise from underneath the dash, I think its the flasher relay, but that only happened when I had the floor charger on the battery, fast start. Has anybody gone through this shat before?? Help!!! Please Help!!!

My truck did the same thing and it was the battery

Yea Rich, I took off the starter and had it tested, it's fine. I took off the battery, which did look old and wore out, replaced it with a Red Top Optima, and BAA, started first try all the time!!! Thanks!!!