PART NO.  SPL.PAGE  DESCRIPTION                                                           
83866     15.O.3    Pipe -flexible -for connector to engine (oil signal hose)
83866     16.O.1    Pipe -connector to engine (flexible) -(oil gauge, instruments,
    std.model, 1600 and 1600-MK-II) -changed to AAA627

83866 Pipe -connector to engine (flexible) -(oil gauge, instruments, std.model, 1500 -changed to part number AAA628 for later models.

Alternate numbers:
Moss part number 376-060
Limora part number 19504

Mating thread for these parts is 1/8-BSP (28 threads per inch) The replacement hose from Moss Motors and Limora was reported to be faulty in October/November 2021, having incorrect thread that would not connect to the male threads on the mating fittings.