Group By Query Problem

["eziokolo"]

This is my Query 
 SELECT 
p.partno,p.vendornumber,p.Type,p.Modelname,p.Modelnum,p.modelyear,p.description
        FROM Parts_all p INNER JOIN Contacts c ON p.vendornumber = c.ID
        Where p.partno = '602510'
        Group by 
p.partno,p.vendornumber,p.Type,p.Modelname,p.Modelnum,p.modelyear,p.description

 Because the Modelname, description and Modelyear have different values, the 
above Query returns multiple partno and Vendornumber for record.

 What I would like to accomplish is to filter the records to return only one 
record where the Partno and vendornumber are the same.

 Please help with examples.

 Thanks