Not really sure what your up to? Are you trying to keep the speed sensor for the TCU or are you wanting the speedo to work? These are two different sensors, one is in the trans and the other is in the t-case. I run duals behind an A340f and all I did was bolt on Marlin adapters and buy a speedo extension cable which connected to the rear case just like stock. Marlin sells the adapter to allow electric speedos to work if needed.
There is a build thread here and on Pirate.
