I was running a Solix 12 SI Mega G2N in the console and went to adding a Helix 12 G1 at the console with the Solix. I want to hook up the Thru Transducer that was hooked to the Solix up to the Helix to run 2D through the Helix 12 along with mapping. The Solix will be used for SI and DI.

Is there an adapter for the hook up or a cable?

Not for that setup. There is one for a Helix 9 pin to the solix 14 pin but there is not 14 pin to a 9 pin

Actually there is. A Minnkota built-in MSI and MDI transducer is a 14-pin connection. To connect one of those to a Helix, takes the Minnkota MKR-MI-1 adapter

BTW the Helix is 7-pin #9 connector.

, thanks I keep forgetting about the MK adapter cables

I have one I need help on I have a Solix 12 Mega Si-Di 1st gen. Want to buy another Solix 12 Si-Di mega G2 Need one set up for high speed sonar thinking in hull or thru hall transducer. Whats the best way to do this correctly.

The hull you have determines what installation is appropriate.
If you have a boat that is a displacement hull you can use just a thru-hull---low and slow.
If the boat is a planning hull and is thin fiberglass, you use a shoot-thru 2D transducer and put the SI transducer on the transom, then connect the shoot-thru and SI transducer to the display with the 14 M SIDB Y cable. 2D will come from the shoot-thru all the time.

Sorry the transducer is a shoot thru