Im looking for belt sizes for a roper rally 11hp 38"deck maybe early 1990s with round headligths

Model numbers help with parts look ups, but try here,

Sears Mower Parts - Roper Lawn Mower Parts at HyperParts.com,

And here,

OEM Replacement parts for Tools, Appliances, Consumer Electronics and more | eReplacement Parts

The last link requires a model number.