See Figures 1, 2 and 3
FLUID LEVEL CHECK
The transfer case should be checked in the same manner as the manual transmission. The level should be up to the filler hole. Use the same viscosity oil as in the transmission. The filler hole is on the right side. Check the oil level at the top hole. The bottom one is for draining.
Some NP-207 models have a two piece fill plug, i.e., a small threaded plug inside a larger one. If your transfer case is so equipped, the fluid level is checked at the bottom of the smaller plug. To remove the smaller plug, hold the larger one firmly with a wrench while removing the smaller plug.
DRAIN AND REFILL
All manual transfer cases are to be serviced at the same time and in the same manner as the manual transmissions. The transfer case has its own drain plug which should be opened. Do not rely on the transmission drain plug to completely drain the transfer case, even if they are interconnected. Once the transfer case has been drained, replace the drain plug, remove the fill plug and fill the transfer case. The Dana and Spicer transfer cases used SAE 80W-90 gear oil.