Here's the thread of a discussion we had on the subject last summer:
http://www.net54baseball.com/showthr...pps+mini+cream
I'm sure AL (the OP on the thread) would've provided the link for you but he's navigating the world so I'll do it in his absence.
Note in the thread that aside from the completed stat back's there were also proofs for this test release. There were cream/white blank backs, brown/tan blank backs and Al has some stat backs with red ink but no green.
Print numbers that I have heard thrown around are that the complete stat backs are numbered at or around 100. Ebay seller gotjacollectibles (who I rec'd my blank backs from and still has some for sale) numbers the white/cream backs at 10 and the brown/tan backs at 5. Al's red ink only back is probably numbered at no more than 5 and is more than likely a one of a kind piece. I believe gotja is also the Allan fellow mentioned in the CU thread.