Turbo 400 not going into park

[cooperhw]

I did try searching but thought I might reach out to my truck brethren and get a quicker/up to date response.
My project truck (Homer) was supposed to have had a transmission rebuild when the truck came through Arizona heading to California after it quit. Well even with the shifter linkage off I cannot get the transmission to go into park. I have researched this issue and have come up with a possible scenario. Supposedly this "parking PAWL can be installed backwards which is what I am believing happened. The motor home was coming from Montana heading to California. Shop "rebuilt" the transmission and seeing as it was in Phoenix AZ it might have been blazing hot and they were moving to San Diego to live there so the owner said fine, let it go.
My question is this; can this Pawl be removed and turned around while the transmission is in the truck and can it be done by someone who is "transmission challenged?"

Any help would be greatly appreciated.