THat's where you want to do it if front shimming will bring it to specs. Double check your gasket thickness at the input candle stick and make sure it
s not too thick allowing the input shaft to come forward creating excess end play. Total end play (I prefer) to be about .020-.025". I have set them a shade tighter and had great success. Some factory books say you can have a tolerance of .040". That's too much. The iron and steel will not grow that much because the whole unit will expand pretty equal. Go thru your mental check list and be sure there is nothing you may have over looked when assembling. If you had to guess, where do you think the end play is at now?