is there anything I can buy or do to keep my guitar from going out of tune when I go to drop d? I bought this new in 1990 & still plays like a dream! That is the only complaint I have with it, when I am in standard tuning I rarely have to retune through a show.

You can try the eddie van halen d tuna. I tried it on my foreign jackson and it wouldnt fit right, so its a $50 gamble if it'll work on the usa model. You pretty much have to re set up those guitar every time you switch tunings. The only other things that might work for you is installing a trem stop (I bought mine from floyd upgrades), keep the guitar set up in standard and then you could switch to drop d without all the other strings falling out of tune and the bridge sinking.

A trem stop is the only way to keep it from going completely out of whack in an alternate tuning situation, the string tension change takes tension off of the trem springs and blocking the trem is the only solution to prevent opening the tuning can o'worms. Unfortunately, it will take the ability to pull up on the trem out of the equation, OR you could just get another Jackson and leave it in drop D...

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Chaos, panic, and disorder.. My work is done here.

You can also install a tremlo-no. it will lock the trem so you can change the tuning with no problem but while it is locked you cant use the trem.

http://www.allparts.com/Pin-Type-Tremol ... 05-010.htm

I use drop D tuning- I use Slinky Bottom Heavy strings, that helps alot, cause I used to have the same problem. Try em, see what happens. ]