Farmall Cub

I have stumbled accross a 300U that has been sitting for a while and has some issues. First and foremost is a stuck transmission. I removed the shifter tower and the rails will move back and forth, but the tranny is still stuck. I am guessing I will have to remove the rather large cover to access the gears. Other that nasty oil, what should I look for or expect to find in there. It has a S serial number suffix, which I think means equiped with TA an IPTO. Other than a couple emblems and lights missing, it appears to be complete.
Any insight you guys could give me would be appreciated. Thanks in advance.

TA lever will be on the left side in front of your knee----lpto (if equipped) ,will be alongside the seat and could be on either side.-----the suffix means that the tractor has provisions for them,--but someone may have ordered the tractor without them!

See if all the gears will slide along the spline shafting in the transmission.---they could be rusted to the splines and will have to be loosened up before you can get it into neutral thanks; sonny