Hi everyone

A newbie here

I have a question and hope someone can help

I have just brought a 2001 f150 Harley model. My problem is a locked up gearbox or diff?. I can move the shifter on the tree, but the rear wheels are locked whether in neutral or not. I can't remove the prop at the mo, as the bolts are rusted and rounded. There are also no brakes due to rotted brake lines. Could the lack of brakes stop the gearbox from exciting park, even though the shifter moves??

Any help would be great, this truck has sat around for to long and it's time for me to give it a new lease of life