1990 Toyota Pickup Transfer case oil

On the transfer case will be a drain at the bottom and a fill plug at the middle, the fill plug also is used for checking the fluid level, it should be even with the bottom of the fill hole, remove the drain plug, let it drain out, replace drain plug, remove fill plug, use Hypoid gear oil with an API of GL-4 or GL-5 SAE 75w-90 weight oil. Interval is 15,000 miles or 18 months whichever occurs first.