I don't think any [56]500 shipped with 7.6, so finding an OEM disk will be a chore. I do recall hearing about a system enabler (was it 411?) that would allow 7.6 to run on such a machine, but I wonder why you would bother when 7.6.1 is easier to find and is more stable...Otherwise only 7.6.1 will work.AFAIK, the 5500 series needs a OEM branded disk to install System 7.6...
Peace,
Drew