look at your differential and you will see that the pinion shaft (input) is either on the bottom side or the top side.
all CJs came with low pinion axles and if flipped they will empty of oil through the breather hole. So you cannot make a low pinion a high pinion.
The major benefit in the rear is it makes the drive line angles after a lift less drastic as rear drive shafts are short. The MAJOR drawback is they make you have to run reverse cut gears that are way weaker.
the major benefit in the front is they make you run reverse cut gears that are way stronger, the drawbacks in the front are few.
If you will envision a set of gears you will see why reverse cut help in the front and hurt in the back. Just as regular cut are stronger in the rear and weaker in the front.
XJs came with high pinion D30s that are a direct swap into a TJ, I do not know of a high pinion that fits a CJ front end, but there may have been one.
