TheSwavu
There are two Mt Mabels in the NT according to their Place Name Register. This one is in the correct location. 

Mt Mabel is 156m on the Rum Jungle 1:50 000 map along with a 164m spot height to the NNW. The 100K and 250K maps were made by copying from the 50K so I think someone stuffed up when they made the 250K map.

The elevations on the 50K map are stated to be accurate to +/- 10 m.

I have added the 164m spot height and fixed the elevation on Mt Mabel.