Was not suggesting you jack it up, just put on high then put jack under chassis with piece of wood between jack and chassis, if it drops which is unlikely, it will drop onto jack and not onto you. Yes by all means leave a door open. I thought you were just checking transfer box, if you plan to be under any length of time it needs to be supported properly. As in, on ramps or with axles lifted and on stands. If you are just checking transfer box oil level it needs to be level anyway. So putting one axle on ramps would defeat the object slightly. Just lift it to high position and put something under it to give you a chance of getting out, if it's only a quick look your planning. Axle stands are ideal, if you don't have any i suggest you buy some if your planning to do work underneath for any length of time.
i need to take off the trans box motor as low range not working may only be the plug or mybe the motor even the ecu but thought i would start with motor