I have a 76 fj40 with a 4spd transfercase. I cracked mine case and started building the spare case I had here. I started looking at the case and it has a 39 tooth idler. I do not have any thing other than the new case and idler. I'm trying to put this case together for a trip coming up. Can you put the 4spd gears guts in a 3 speed case ? I tried but the thrust clearance is tight. I have .114 " without thrust washers. Can this be done? Not even sure I have a 3 speed transfercase. Pictures are attached. The date code didn't make sense to me.