The instructions are the same for both the Np231 and Np242 transfer cases. I apologize for the bad shots...having a hard time getting it from the .pdf document to a program that would actually let me convert the image to something useful. Np231 (Command-Trac) Np242 (Selec-Trac) To drain, first remove the fill plug (that way you're positive you can get new fluid back in there...nothing like removing the old fluid only to find out the fill plug is stuck on). Once the fill plug is off, remove the drain plug and allow fluid to drain out. Once old fluid has drained, re-install the drain plug, and fill the t-case back up with the appropriate fluid, via the fill hole, until it reaches the bottom of the fill hole (or begins to run out). BOTH the Np231 and Np242 require Mopar ATF +4 type 9602 Automatic Transmission Fluid. You can probably get away with using another type of ATF +4, but i probably wouldn't risk it with something as important as the transfer case. Remember to get ATF +4....not +3 or anything else.