Please note that we have a mounting kit search tool on our website at www.parkermotion.com and www.baysidemotion.com > on the right side, click on Motor Mounting Search, select the Manufacturer & Model number, and then the gearhead model and frame size.
It is also linked to from the product pages under Part Number Configurator > Gearhead Mounting Kit Search Tool. This search tool shows the mounting kit adapter thickess (AD).
If you have a mounting kit but don't know the motor, you can use attached spreadsheet to find the thickness: