Bought an 85 Ford F250 truck has minimal issues, batteries are old and will be replaced soon but I have needed to charge twice. Started right up this morning in 22 degree weather shut it down and went to re start 2 hours later and it needed to be charged, started up 20 minutes later but when I went to engage the clutch to put the truck into gear it made an awful noise (not a grinding or high pitched noise sounded more electrical) and all the interior lights started to dim or blink but noise stopped when the clutch was released. Never had any issues before this and it's a brand new clutch and alternator. only issues I've had are with the batteries. I have driven it a couple times since buying it with no issues, any ideas?

 

Were there any issues after the alt and clutch were replaced?
How much time has passed since that work was done?

To your knowledge , at the time the clutch was replaced , was the release bearing replaced also?

So we are on the same page, the clutch is engaged when your foot is off the clutch and when you depress the clutch pedal you press the release bearing against the clutch assy to disengage the clutch.
The release bearing is always replaced at the same time the clutch assy is replaced.
Can we ask who did the clutch and alt work?
If you hear any unusual noise when depressing the clutch , it usually is coming from the release brg.
If the alternator locked up because of bad bearings it could cause a squealing noise which if not stopped and could burn and break the fan belt.
What is unusual is , why the lights dimmed when the clutch was depressed, if, that is what happened.
You say batteries, is this a diesel powered vehicle?

 

So the clutch and bearing were replaced in 2014 and the alt this summer. the truck did sit for a bit but got a good amount of work done to get it back running. And the noise happens when the clutch is pushed in. The work was done by the previous owner. And yes this vehicle is a diesel.

 

From 2014 to now that is plenty of time for the lube in the release bearing to dry out. Might explain why noise when clutch is depressed.

What is enough to scare any tech is when someone says,
"Got a good amount of work done on it". Anytime somebody gets into areas doing repairs which we have no idea what they did or how well. Just another possibility for another problem..
What you might do, have someone depress the clutch pedal and you look under the hood in the engine compartment and see if that pedal linkage is touching any wiring.
May have a hydraulic clutch system, You may also need to look inside the cab to see if that pedal has any opportunity to hit any wiring when it is depressed.

It is an 85 with plenty of time to rust and have help from rodents chewing on wiring. There has to be a reason for the lights dimming and it could be something like a poor ground connection to something contacting wiring to cause direct short to ground .

From my recollection , those years were susceptible to rust and poor connections. If there is a starting problem, a poor connection could be the real problem instead of a battery problem.
What does the engine compartment and fender wells look like. If rusty , you might start there and install some new ground wires to eliminate that possibility.