The hubs fit, but the problem is the snap rings on the axle shafts go on before you put the hubs on, on trackicks.....and you have to put the hub body on, then the snap ring, then the cap on the hub, on samurais. So the problem is that usually you have to space the samurai hub out, when you put it on a trackick....so the inner part of the hub doesn't bottom out on the snap ring. Most people just put 2 paper gaskets between the hub body and the wheel hub and the hub to snap ring clearance is fine.
For the samurai front axle, the 86-88 front axles are better, because they use 3 pin carriers, instead of the single pin carriers, like found on the 88.5-95 samurais. The 3 pin carriers have bolts that hold the end cap onto the carrier. The single pin carriers are held together with the bolts that hold the ring gear onto the carrier.
You can actually remove the oil fill plug in the axle and look at the end of the carrier. If you can see bolt heads, then you have an 86-88 axle with the 3 pin carrier. If you can't see bolts, then you have the later axle with the single pin carrier.
Other than the carriers (and sidegears in the carrier), all samurai front axles are identical.