Not sure how much is "within spec" but on a new or rebuilt T5 there is barely perceptable movement. The main cause of this movement is wear on the roller bearing between the input and output shafts. A cheap part but not so easy to replace. In some cases the bearing surfaces on the input or output shaft will be worn which will make it a lot more expensive. I had my 150,000 mile T5 rebuilt by Bob Hanlon and it only needed the bearing replaced to eliminate the movement. Of course a lot of other parts were replaced at the same time.
http://www.hanlonmotorsports.com/
Great service and fair prices. Bob also has a T5 rebuild video that he will sell you along with complete rebuild kits or new/used transmissions.
Mike...