How do you change fluid on 1998 Nissan maual transmission?

Put truck up on jackstands (good ones, be safe!) The drain plug is on the bottom of the trans I use a 1/2 inch breaker bar to get them out, the fill plug is on the side of the unit. I break the plug loose and then put a catch pan (big one) under the plug prior to removing the plug. Agian "prior" to removing the plug, the bigger the pan the smaller the mess you will have to clean up. To refill the unit, simply reinstall the drain plug and remove the fill plug (again on the side of the trans) and pump in the new fluid, a fluid tansfer pump works the best. (Northern Tools, Harbor Freight ect.). Good luck and make sure you put back in the proper fluid, owners manual or a call to the dealer will tell you what your specific unit needs.