Jeep offered a full-size Wagoneer in the late 70s - early 80s, and there was an XJ Wagoneer from '84 thru about '89 or '90, so when you want to know about GRAND wagoneers, it's best to specify Grand Wagoneer.
Front axle will interchange with XJ but it's low pinion so it isn't an improvement. Rear axles are couil spring, so won't fit w/o mods. And they're either Dana 35s or waek aluminum Dana 44s, so not worth the bother of fabbing new mounts. If you find one with rear disc brakes and want to convert your XJ, that's a possibility. Other than that, not much interchange. Steering box, I guess, and engine. Tranny is different.