Np231 Has me Stumped (Well Sorta)

So I just swapped out my Np231 in my 1998. I got the replacement from a guy in a local club I am in, It came out of a modified 1994. He said he thought the case was stock, but after I got it all installed, I realized that I have 2 2wheel drive selections. The second selection feels like it is deeper gears. My selection goes like this (2wheel high-2wheel(????)-4high-neutral-4low) It is definetly a distinct extra selection at the shifter, and on the case. Does anybody have any clue what this is or could be. I was thinkink Tera2low, but I thought that tera's 2low was between neutral and 4low. Are there any other manufactors that have this type of selection. Or is it something else. Any help greatly appriciated.