Measuring input shaft end play with trans in the car???

Just heard that when you replace the bearing retainer on the T-5, that you need to check the end play and possibly shim the bearing more. I assumed that the parts were machined the same and that this wasn't an issue. Do I have to pull the trans again and check this or can it be checked with the trans installed?

Can't I just pull on the tail shaft and see if there's play? Didn't the 94-95 T-5's come with the steel bearing retainer already and if so, shouldn't they all be the same?

Thanks again!