I have a 1988 F-150 with a straight 6, It seems to have a 3 volt draw from the battery with everything disconnected. Not sure if it is from the computer, if it even has one, or what it might be from.i could use a little help! thanks

 

When you say everything disconnected, if you actually disconnected everything(pulled all the fuses) then the only thing left is the alternator. If you disconnect the alternator and the drain is gone , you will need to replace the alternator itself. Let us know what you found.