Depending on how the Yj is lifted, the longest shaft may not be the best way to go. If it is lifted with shackles with the flat stock leaf springs the distance from the axle to the TC will decrease with compresion of the suspension and could cause an impact to the rear of the TC. With lift leaf springs this would not be such a problem since with compresion of the suspension the distance from axle to TC will decrease in the vertical direction but increase in the horizontal direction, somewhat canceling out.