Transducer shield

Anyone know where I can get a Transducer Shield and Saver for a Humminbird 898

Just do web search for Transducer Shield and Saver TM-HDsi

I am looking for something like that to mount on the Transom of an Aluminum boat

You can use that mount several ways.

If you want it directly on the transom, the best option is with the Spring Back Bracket.

https://www.transducershieldandsaver.com/product-category/spring-back-bracket/

If you have a jackplate, you can use their L bracket that matches the jackplate. They are listed by jackplate brand----

https://www.transducershieldandsaver.com/product-category/l-brackets/slidemaster/

I have a Tracker and have used just the Saver attached to the underside of the transom step.
This is the ONIX HDSI transducer------

BTW you can get them directly from Transducer Shield and Saver.