I have a tool for lining up the clutches in Polaris machines...probably won't work for the old TNT though the principles should be the same. Maybe you can use a pocket laser to get it close?
i"ve seen it done and also did it myself by using a peice of ready rod and laying it on the secondary clutch and up to the primary clutch,or use a laser level.on those old machines you did not have to be that accurate,never wore belts and seemed to work ok