How to obtain old version of HBA firmware ?

Hi all:
I have a need to down-rev my AIX HBA firmware due to storage instability after upgrading, but IBM support only makes the latest version of firmware available for download.

Can anyone provide pointer/tips for obtaining old HBA firmware ?

Specifics:

280B HBA
df1000fa driver
1.90a4 firmware     <<< looking for this version

Thank You,
KenW

pSeries boxes come with a load of CD/DVD media. Among them is a CD with all the firmware for every type of box and adapter. However, you are looking for a pretty old CD as 1.90a5 seems to be from December 2006 ...