There was a MOS thread on this:
If you really need to know what startCD you used, you could also check your FMW version ( that is if you haven't upgraded it since the install).
188.8.131.52 Start CD 51
184.108.40.206 Start CD 50
220.127.116.11 Start CD 49 or 48 - if you still have Jrocket then it was start CD 48
Check as suggested by mdtaylor
Before that on the same question i have raised the SR but no luck, Service engineer stated as its not possible
Thanks for the update. I got and it is 51