90 was the first year for EFI.
88.5s have square vents in the dash, a different instrument cluster, larger bolts and bolt patterns on the driveshafts, a single crosspin carrier in the front axle, a lower 5th gear ratio, 3/8" (10mm) square drive drain and fill plugs for the axles, tcase and tranny, a single rear rubber brakeline, different connectors on some of the wiring harness plugs in the engine bay. There may be more differences....but that is all I can remember off the top of my head.
Yours may have all, some or none of what I listed above.....88.5s were transition samurais, so they were changing parts as they ran out of old stock.
