I've got an 88 s10 blazer with the 4.3

The other day it ran just fine in the morning, but by the after noon it wouldn't start.
I went to fire it up and got one click. I figured I killed the battery somehow so I got a jump and it ran just fine no stalling or stuttering ran like it always did.
I turned it off, left it off for about 10 minutes and it did the same thing, one click.
I jumped it again and again ran just fine
And today the same thing.
Now I've changed out the plugs, wires, battery, coil, normal maintenance and all in about the last 8 months.
I had the alternator tested while the truck was running and it read 14.0

Any ideas? I don't think its the alternator. Could it be the starter? I also pulled fuses. Looked for any sketchy wires in the engine bay. I'm stumped lol

Help?

If it matters at all, its 4x4 and only around 122k miles.

 

could be the starter. Could have developed dead spots that are simply powered through with the current from 2 batteries.

Have you changed the battery since the problem started? unusally the battery is the first suspect, have it tested at your local autoparts store

 

The battery was changed around December of last year, brand new. And the problem only started like 2 days ago. Tried again this morning and nothing. I'll have the battery checked out. Could low oil be an issue? I've had a leak for a few months but nothing serious.