I had a LSS 2 set up in my boat with GEN 2 non touch units hooked to it. I upgraded and got a HDS 12 GEN 2 touch unit and removed the LSS 2 module. I think my transducer is going bad and I'm not sure which transducer to replace it with.
Any suggestions would be helpful.

Replace it with another LSS2 transducer. This transdcuer will plug directly into the back of the sonar (not extra module needed.). This will give you side and down scan.

You will still need a standard 2d transducer as well. Your standard 2d transducer will have the blue connector.

Link for Lss2 transducer

https://www.cabelas.com/product/Lowrance-reg-LSS-Skimmer-Transducer/1579434.uts

Thanks Javelin.
I sent an email to lowrance and they sent back that I need a HDI transducer that didn't look anything like the LSS 2. My stuff is old and I thought maybe that was some new transducer that would do the same thing but was a lot smaller. I'll just stick to what I know and get another LSS 2 transducer, my 2D is still working fine.
Thanks again.

The HDI transducer only does downscan and 2d sonar. People will often use this transducer on the trolling motor or if they dont want sidescan.