Hi Joey

You would possibly be looking a Riley Fitting, RM 85, Pin type gooseneck with slide to fit RM 103 track, spring loaded plunger pin locates slide in position on track. Pin diameter 9.5mm. Find someone who stocks Riley, possibly whitworths.com.au or binksonline.com.au, and you can buy over internet.

Regards

Matt Harper Homebuilt Taipan 4.9 AUS 329 'GOT WOOD' SEEDY PIRATES RACING TEAM