If the 300 has a console shifter those cables won't work on your push buttons, if it has the push buttons you should be good.
Those trannys are real sensitive to the adjustment of those cable shifters', one bolt hole can make it out of adjustment: shock:
I take the tranny pan off to adjust the shift cable, disconnect the retainer on the pin on the shift cable end that moves the arm that moves the manual valve in the valve body and then put the shifter arm in neutral and adjust the cable housing with the adjusting wheel so the pin drops perfectly into the hole in the shifter arm, perfectly every time
Have fun, take your time and look at it real hard before you start and make sure your very happy with the adjustment when you're done