The flowmaster and K&N will be of no help to you for your purpose. A locker in the rear axle would provide the most benefit. If this is to be a daily driver, I'm make it a selectable locker, rather than an automatic locker. But that will cost you -- maybe between $600 and $800 for parts, and another $250 for labor.

But even with a rear locker, you're going to be disappointed in the mud or any serious off-roading. I'd advise you to trade in your 2WD on a 4WD model.

1977 CJ-7, fiberglass body, AMC 360 w/ headers, DUI ignition, Edelbrock intake and Holley 4150 carb, TF999, Dana 300, 4.56 gears lockers, York air comp, 4" susp lift, 2" body lift, BFG 35" M-T tires, Megashifter, AGR pump & box, REP8000 winch.