1995 grand Cherokee laredo power drain

so i bought my aunts used 95' grand cherokee laredo with the idea of having it as a winter beater... weel I have been unable to track down a voltage bandit... I put a barnd new battery in it not too long ago, but the jeep whenever i leave it sitting for more than a week has a dead battery.. I have tried various methods, checking grounds.. removing & checking fuses.. but the issue remains.. I do have a "rear lamp failure" in the indash display... but harldy believe that is the cause of the issues. any ideas or hints??

Try unplugging the radio from the harness. I have seen defective radios cause this problem.

Agreed on radio. Also, in my owner's manual it says that the battery will last 2 weeks before being discharged. I'm thinking that with an older vehicle the drain may occur faster. Either start it up every few days, or disconnect the battery.

The tail light issue could indicate a short, but I don't see how it would drain the battery over time.