1992 Safari - Parasitic Load on Battery?!?

Need some advise on how to troubleshoot unknown complete parasitic power drain on battery overnight:

Test drove vehicle at sellers. Several easy starts. Noted no power to passenger side window, air con not working, dome light missing, brake lights not working. Drove home, parked for 2 hours, started up fine. Noted oil pressure gauge behaving irraticly when rpm's increased. In the morning battery completely drained. Got boost. Found broken hazzards fuse and replaced, all expected lights now working. Noticed (abnormal?!) slight increase on load on battery/alternator when brake pedal pushed. Left running for 20 minutes, shut off, started up again fine after 5 minutes. Removed battery and slow charged it for 8 hours, replaced battery. Did not attempt to start up for the rest of this rainy day. Crossing fingers for morning attempt to start. Any help would be appreciated as to what the problem might be if it is drained again in the morning. What is the best procedure to test for a short in the wiring or anything else it might be. Thanks in advance for your input.

To check for draw on a battery, a quick and easy way to determine which circuit is at fault, try the following procedure: Disconnect the negative battery cable at the battery. Connect the alligator clip of a 12 volt test light to the negative battery post and the other end of the test light to the negative battery cable. With a fully charged battery: If the test light comes on dim, it is indicating normal parasitic draw, (KAM or keep alive memories). If the test light comes on full brightness, you have a 12 volt draw that can drain the battery rapidly. Start pulling fuses one by one until the light either goes dim or out completely. Now you know what circuit to trace. If you're not sure if the test light is at full brightness, open a door, blow the horn etc... something to create a known draw on the battery. If the light doesn’t get brighter, something else is trying to draw current from the battery. I might add that during your test, make sure ALL lights, accessories, and the ignition switch are off, and the doors are closed, or at least hold the pillar switch in, or disable it. NOTE: This test can be done more acurately with a multimeter that has amperage testing capabilities, connected in the same manner as described above. Rule of thumb is anything more than approximately .2 amps will kill a good battery overnight. Your neighborhood dealer will have the normal parasitic draw specifications for your vehicle, whether they give them to you is another story.

Thank you so much for your reply. The testing method you described worked! I found that the parasitic load was on the Horn circuit and trace my problem with your help. All is well... for now ;-) Thanks again.