Someone needed to replace a rusted rear exhaust hanger once, so here is a template. Click for larger printable image. It should be very close to full scale when printed on A-size paper (8-1/2 x 11 inch) with minimal margins.

Template provided by R J Brown in Colorado, USA.
Photo provided by John DeWolf in Canada

Addendum 3/7/2020: To avoid confusion, the flat mounting surface is to be straight up vertical when installed.