2 separate things.... derailleur hanger (there are Hundreds for various bike brands models ) get one, then pick a chain tension-er...
Low end, old stuff, Shimano for example, has a simple stamped steel one ...old bikes did not make it part of the dropout.
It's Steel held on by the axle nut dropouts were more horizontal , longer, then..
running the Hi & Lo stroke limit screws inward can turn a rear derailleur into a chain tensioner .. for little money. if any..
....
Last edited by fietsbob; 08-15-17 at 11:33 AM.