first your 86 is not a cj5, 81 or 82 was the last year for the 5. The trans will bolt to the engine side of your 72 engine but you may have clutch linkage issues to sort out. The 80,s cj used a dif tcase than the 72, the 72 used the dana20 tcase or a left over spicer18, the 86 used a dana 300 and hangs down lower than the 20 or 18 so you will have to swap skid plates as well. If you have the dana 18 tcase then your rearend is not centered and the dana20 or 300 will not work unless you swap rearends (you probably have the centered d44 and 20tcase). If you have the dana 20 tcase in your 72 and want to keep it, this swap will not work with out a tcase adapter, the 20 and 300 have dif bolt patterns. It should work if you leave the 300 with the trans