PART NO.  SPL.PAGE  DESCRIPTION                                                           
300398    15.R.18   Washer -(copper seal at union at pump return -(heater, optional,1500)-
    changed to AAA4657 for 1600 model
300398    16.R.46   Washer -(for union at pump return, heater, 1600 and 1600-MK-II)-
    changed to AAA4657

300398 Copper sealing washer (crush type). For heater return water spigot to 3-way pipe in coolant near water pump inlet, MGA 1500. Part number changed to AAA4657 for 1600 model.

Alternate numbers:
Moss USA number 324-660 :
Moss UK number 232043A