welcome to the site! You might post in the welcome forum and introduce yourself and your truck.
A lot of the cab parts (dash parts especially) are the same as for the smaller trucks. Is this the knob and shaft you are looking for?
https://www.ebay.com/itm/155139488772as far as fixing leaks, clean it all real well, watch for where the leak starts (top and front, and it almost always flows down and back). Trans is easy to drop and seal, valve covers and intake are prone to leak, and then there are always the front and rear main seals on the engine.... just depends on how bad it leaks and if there is other maintenance needed that requires dropping trans or pulling engine!
Park brake boot, good luck!
