Hey....hitched a ride to work this morning cause my 64 Valiant isnt shifting properly. Wouldnt reach 3rd and is slippery getting into 2nd. There is fluid. What do I check out first? Thanks.

I would check the kickdown linkage first, make sure something did not get loose or disconnected.
The next step would be to drop the trans pan and change the filter, a clogged filter or loose valve body can cause a low pressure condition.
After that it's pressure test time, see a FSM for details on this.
DD