AFAIK, all of the '89s route the o2 sensor over the transmission to the driver side frame rail mount near the t-case.... a harness runs from the frame rail connection forward, then up and into the engine bay where it joins the run into the main harness. I suppose it's done that way to keep the harness away from high heat.

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum