Diesel Bombers - 6.5 Turbo Diesel Won't Crank

I have a 1995 6.5 turbo that won't crank. Drove it a week ago Saturday without issue. Stop and started multiple times. Got up to go to church the next day and nothing. Went out to check again later in the day still nothing. I could hear a clicking noise when I turned the key so I assumed it was the started. I check all battery connection and they were good. Just put two new batteries in during the month of November. So I took the starter off and got another one under warranty. Put that one on and it did the same thing. I can hear a click each time I turned the key. I took that starter back and got brand new one. The others were remanufactured. Got that one on, made sure all connections were tight and it did the same thing. I can hear a click each time I turned the key. The sound more a medium tone and it makes single click it time I turn the key. I also check to make sure the engine turned freely using my flywheel tool. Not sure what else to try. Any suggestions.