I guess it falls to when they were made. The model E was introduced first, with its hammer tone paint right after this model was retired. Like any factory, the aluminum buffing department was the most costly because of all the accidents involving the huge buffing machines. Anything a manufacturer could paint as opposed to buff, would be a welcome change. The exhaust cover on mine is chromed, as is the switch cover. The model 61 was the top of the line machine when this model 30 was current.