Km110 stuck in 3rd

Not a d50 question but it’s related. There’s a lot of knowledge on here so I figured I would try here.

I just swapped my 78 colt from auto to manual dropping a km110 in it. When I pulled it from the donor car it rowed through the gears fine sitting still. I dropped the pan, replaced the gasket, changed the real seal and put fluid in it. Got it in my car and now it is stuck in 3rd. The shifter is off of the trans, but I can not get it to budge out the 3rd even with the shifter on it. Placed it on stands and ran the car, and I still can not get it out of gear. I checked the fluid and it’s at the proper level.

Any one have have any suggestions on what I can do? I am going to have a very hard time finding a local trans shop that will touch it because of the year and the fact that I converted it to manual. I have a factory service manual that has exploded views and descriptions of everything, but I am no means a transmission guy. I could pull the pan off and look for obvious stuff.

If if I could find a km119 I’d drop it in, but I’ve had no luck getting one locally.

Any help would be greatly appreciated!