This is the first time I have ever attempted to replace the IOS on a 6509 so I am taking this one slow.
"dir flash:" shows the following image: cat6000-sup720k8.8-1-3.bin. The new image is: s72033-ipservicesk9_wan-mz.122-33.SXH2.bin. There is a considerable difference in size here. The first image is 13MB, while the new image is 72MB. Does that seem correct?
The two images are obviously for the Sup720, but is there another image I should be aware of or just sup engine?
cat6000-sup720k8.8-1-3.bin is a CatOS image. If you have an MSFC card ie. your 6500 routes as well as switches then you are running in hybrid mode.
s72033-ipservicesk9_wan-mz.122-33.SXH2.bin is a Native version.
Difference between hybrid and native
Hybrid = CatOS on supervisor/IOS on MSFC
Native = IOS for both
Have a look at this attached link which outlines how to upgrade a 6500 from hybrid to native mode.
Be aware that your configuration will also change as all the CatOS config needs updating to IOS config.