1966 mustang convertible-302-steering box just changed-steering wheel still does not return to center position any suggestions-thanks

 

Do you mean the car does not track straight ahead with the steering wheel held centered, or that the car "pulls" the steering wheel off center
when you let go of it?

Likely the first case: you have the steering wheel installed "off-center", possibly due to the new wheel not having an aligning key like the original.

 

steering does not pull either direction-car tracks straight-front end aligned correctly-steering wheel not off center-tires and rims road balanced

 

Two ways to fix that.

1) if it's really off, Make certain the car is going straight (regardless of steering wheel position and then remove the steering wheel and clock it the number of teeth required to center it.

2) If it's only slightly off, you can turn the Outer tie rod ends the identical number of turns in th correct opposite direction of each other to center the steering wheel. https://www.quicktrickalignment.com/...teering-wheel/

Example. If the wheel is cocked to the right when the car travels straight ahead (wheels point left when the wheel is straight), you'll turn the dirver side outer tie-rod Left (lefty loosey) X number of turns to lengthen that side, and turn the Passenger side outer tie-rod an equal number of turns to the right. (Righty tighty) to shorten that side. It's the opposite if the rack is behind the center of the wheel like in a FWD vehicle.

If you have an older setup without a rack here's for the box:

yet a third way is the shaft rag joint but I'm not as knowledgeable on that one.

If you really want to get technical....