how to tell hard drive fit macbook ?

TOSHIBA MK5065GSX 500GB 5400 RPM 8MB Cache 2.5" SATA 3.0Gb/s Internal Notebook Hard Drive. Taken out of a new 2011 Macbook Pro.

will this fit MacBook Pro "Core 2 Duo" 2.53 15" (SD) 7xj being the last 3 digits of serial #. how to tell ?

Yes it should. The reviews had a few people who had already replaced them in their MacBook. If it's a 2.5" drive it will generally fit just fine except for the 1TB 2.5" drives. They are too thick. I think still the largest drive that will fit is a 750GB due to the drive thickness is too great with anything higher.