Hello all, now that the weather has finally dropped under 100 degrees I am tinkering with the Montero again and I am in need of more advice.

My 5 speed used to run through all the gears just fine (not running), I changed the gear oil in the transmission and "lost" 3rd and 4th. Unfortunately I changed the oil prior to the engine running, so I do not know if it would have been an issue prior to the oil change or not.
Now that I finally have the engine going (yay!), I cannot get the transmission to go into 3rd or 4th even when not running. I pulled the shifter assembly and the little plastic piece is intact on the end of the shaft.

Oh, one side note. I started in 4H to test the front hubs, and I thought I put it in reverse, but I almost stalled it because it was in 4th. Why would it go into gear in 4 wheel drive and not 2? 3rd just seems not to exist at all - but I know I ran the shifter through it prior to the fluid change/engine install.

I did search and the closest thing I could find was "popping out of 4th" a few years back. Everyone said the synchros, and I think whoever it was lost everything but fourth a couple months later.

Is it time to find a transmission or did I put the wrong fluid (80w-90), or not enough/too much fluid in? Also, the stuff I drained out was not gear oil, it was much thinner, I would say 10w-30.

Thank you once again for your time,
Ryan