and the e-brake isn't all the efficient, especially if some gear oil has leaked onto it (very common). Keep in mind too that the e-brake does not actually apply any true brakes, it attempts to lock the driveshaft, a very different thing. Having driven many cars in my lifetime with that type of "brake" I will tell you what can happen, especially under somewhat slippery conditions, such as rain, ice, snow, mud, or gravel. The e-brake locks the driveshaft but the wheels keep turning, one frontwards, one backwards, because of the spider gears. As long as one tire has less than ideal grip on the surface this can happen with the result that you have no way to stop the vehicle.
I'm a bit of a stickler as far as keeping these jeeps as stock as possible mechanically but this is one area where I will pay homage to caution and update the M/C.
Larry