My 86 F150 w/inline 6 needs jumping to start.

It does sound like the battery. Did they use a load tester on the battery?

Thanks for the reply. The battery and the alternator was tested. The person at Auto zone told me the alternator was testing bad so I got a jump and went home. On the way home the truck was running just on battery and it almost went dead. I took the alternator off and took it in to have it tested. It tested good. I then took it to Advance and it tested good there too.

I'm sorry ytlas. I don't know what the device was called but the clerk brought out a small hand held tester, nothing on wheels and it tested good. I think it is called

A load tester like I have is rectangular, maybe 4" x 12" and it's hooked to the battery and then a toggle switch is turned. The coils inside the tester get hot because it's putting a load on the battery. If a person uses a multimeter on the battery and it reads 12.5 volts or better, that still doesn't say anything about the cranking amps of the battery. A multimeter is good for checking the alternator. You can put it on the battery when the engine is running and if the meter says 14.5v or better, the alternator is charging. Lot easier than pulling the alternator.

It's like this http://www.amazon.com/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0/ref=sr_1_1?ie=UTF8&qid=1419706890&sr=8-1&keywords=battery+load+tester

It sounds like he used the load tester and not the multimeter, I know what that is.

If you have another vehicle, how about taking that battery and sticking it in your truck to see if it fires? That should prove once and for all whether it is or isn't the battery

I am now waiting for my friend to come over and put the alternator back in.

If you're still having problems, it might be a bad voltage regulator.

I found the problem. A loose connection at alternator. Thanks for the assistance everyone

Change your starter the starter can short out and burn alternator and battery both up if it has a solenoid on firewall it very well could be it but I personally would start with the starter