I would not recomend at all getting a used T5 or a "rebuilt" T5 off of ebay. I bought a "rebuilt" one and the synchros were all bad and it was not shipped correctly so when it was left on my doorstep, it looked like it was rolled all the way from CA. There are so, so many different T5's made and you really need to do your homework when purchsing used.
The best decision I made was to get a new T5Z from Summit. So far it has handled my 351 very well. It is a blast to drive and it is nice to know it won't jump out of gear like my "rebuilt" ebay one did.
Shipping a used T5 is as expensive as shipping a new T5 and you wont have to worry about sending it back.