Always best to be in the habit of comparing the new parts to the old parts, worn out or not.
In this case, if the old one fit you'd know for sure that the bracket was ok. In a side by side comparison, if the new idler body was shorter you'd know you either have the wrong part, or would need a shim. Or if the old one was shimmed you'd know that's probably what you'd need to do on the new one. A quick side-by-side could have answered a lot of your questions right off the bat.
