thats what im thinking Joe

Back to the lights pulsing. A lot of Ford cars had that problem around those years. I used to work as a tech in a Ford dealereship. I don't recall it on any trucks. But, car people complain a lot more. There was a TSB for it. Don't remember how it went now. It was a bad fix. It took care of the problem now, but it was going to cause problems later. I agree, check your grounds.

your battery light
 

The promblem is the the plug on the back of the alternater here is the NAPA part number CE
261. I had the same promblem with my 450 it drove me insaine change the plug no promblem. One other thing the plug comes with 3 wire's your truck may have only 2 just match the position and let her ride.

i used to work at a napa store and we sold a lot of battery cables for the PSD trucks. just something else to keep in mind.

all is fixed as for the bat. light, i didnt have the plugin all the way down. so that fixed that, ive been too busy lately to look at the belt issue, but im going to soon, thanks for the help so far.f

keep us posted on the belt issue

Good too see that the battery light was a simple promblem. As far a the pulley promblem with the belt my best guess is would probably be is that one of the pulleys is out of line just enough to cause the promblem. My best guess would be the balancer.