Historically, the download of ANY+ zipped file such as a patch or a firmware bundle will have a README included that has such historical timeline information.
On that page you have linked, I see references to:
Sun Blade X3-2B (formerly Sun Blade X6270 M3)
Sun Server X3-2 (formerly Sun Fire X4170 M3)
Sun Server X3-2L (formerly Sun Fire X4270 M3)
Pick whichever is appropriate and proceed to examine what's available within the downloaded zipfile.
If the information is missing use your MOS credentials, log a SR, and speak to the company directly.