Car shifted into gear when in park...

Tom Hand's book on Chrysler automatics might be helpful.

That might be the missing spring off the accumulator, that's causing the mega hard 1-2 shift. P.O. might have left in the pan so it could be reinstalled.

The accumulator spring toss is a common poor man's shift kit.

Edit, that spring is way too small to be the accumulator spring. Nvm.