[MoparNorm]

You can determine that by calling your local Jeep dealer's parts department with the VIN number, or by pulling a wheel and measuring the drum. There might even be a visible part number on the drum, if it's an original drum.
Brakes were axle specific, so the year isn't much help for that year.

 

[poorboy_616]

You two options for drums

9 x 2 (I think) and 10 x 2.5.

If you have the trailer package, you probably have the bigger brakes.....