1987 Mack twin stick

Ok after a trip way back in time I figured it out the stick closest to you you will start out in 1st gear the other stick iif you are loaded or off road go to the lo postion the when you get ready to stift you move this to the direct postion then the next shift will be on the main stick and thais will be the only one that you will shift while on the road traveling . Good luck and hope that I did not mass confuse you . Tony