car pulls to left

Not sure why the gearbox would cause the pull; have the tires swapped left to right on the front and see if the car pulls right...you could have a faulty tire causing a radial pull. Also, find out what your caster readings are - your alignment print out should be provided to you and should state the readings. Left to right should have less than 1 degree difference between them, or it will pull to the more negative number. You may want a second opinion on your alignment, as well.