86-88s have 3 pin carriers in them. The 88.5s-95s have a single pin carrier. If you plan on putting a locker in, then I'd go with a 3 pin carrier axle. If you happen to pick up the later axle with the single pin carrier, you can swap a third, or just carrier, from an early axle into a late axle.
Other than the carrier, all 86-95 samurai front axles are the same.