I know you can kick your spicer 18 into rear low after you take out the d. ball but can you go front axle only like a D300 or Atlas?

Okay, heres how it works. The 18 puts power to both outputs through the intermediate shaft. This means that it never uncouples like the 20 and the 300 do. Basically because of that you can not put the rear in neutral and the front in any other gear. Your levers are 2wd 4wd and high, neutral, low.

Thanks for the info!!