I have a 350TH transmission with a floor shifter what is the back-drive lenkage for is it for the neutral safety switch? also after i installed a tilt
steering column i lost the gear indictator what could that be?

The backdrive linkage connects the shift arm on the trans with the lil arm that sticks out of the bottom os the stock column.
It handles:
neutral safety switch
backup light switch
lock in park when you take the key out.

On some cars, my ole 75 monte comes to mind, it also handles the gear indicator, which was in the speedo on that car.

i could not get it adjusted right. the car would not go into low then i would adjust the other way and i could not get park. do i need to try harder or what is my next step. thanks for the help.

i could not get it adjusted right. the car would not go into low then i would adjust the other way and i could not get park. do i need to try harder or what is my next step. thanks for the help.

The idler swivel that is on the frame is different between a TH350 and a Powerglide. If you have the wrong swivel you will never get it to adjust correctly.