The AX-15 was a mid year running change , partway through 89.
Easiest way to tell what's there is ...... the poogeut has a seam down the lenght of the main case , in other words , the two halves of the main case are positioned side by side , the parting line is easy to spot. The AX 15 is of a more conventional build , the sections are separated fore to aft , there is some webbing on the main case to make it stronger.
If the YJ is late 89 , it should have an AX 15 , if the original doors are still on it , it's quite possible there is a build date / spec sticker on the rear portion of the inner door.
For example , .... according to the decal on the door , my 94 was built in the spring of 94 , making it a late build ............... important to know when buying a starter ( don't ask how I know ! )