The skip shift function is already disabled (ECU tune and skip shift delete plug), making the skip shift solenoid itself obsolete. The previous owner had cut off and blanked the electrical connector, but that did not stop oil seeping through. While the solenoid was accessible, I decided to replace it with a simple plug (saves some weight too!)
The skip shift solenoid thread is M20x1.25, which happens to be the same size as a Subaru EJ oil drain plug. Unfortunately a bit too short, but I solved that by some DIY machining, allowing the bolt to seat on the chamfered edge in the transmission. I also applied a thread sealant.
