Lister Petter Swivel Union Plug 366-07039,commenly used with the T series engines.366 07039 Swivel union plug commonly used with the T series engines. This adapter was used with accessory kits LG and LF in the TS and TR line of engines. This will be item number 1 in the Lister Petter drawing. Make sure you order 2 copper sealing washers when replacing the adapter, part number for the washers will be 616 01608 Warning; Do not over tighten this adapter as you will twist it off inside the engine block, this is a very common mistake