We use these in all our spec cars to simplify the cooling system.  These plates bolt to the back of the M20 head allowing you to delete the heater hose connection. 

Kit includes:

• 1 Block Off Plate
• 1 Gasket
• 1 Hose Block Off
• 2 Bolts
• 2 Washers

This item fits:

M20B20
    1977–1981 E12 520/6
    1979–1983 E21 320/6
    1982–1984 E28 520
    1982–1988 E28 520i
    1983–1992 E30 320i
    1988–1990 E34 520i

M20B23
    1977–1982 E21 323i
    1982–1985 E30 323i

M20B25
    1986–1993 E30 325i, 325iS, 325iC and 325iX
    1989–1990 E34 525i
    1988–1991 Z1

M20B27
    1982–1988 E30 325/325e/325es
    1982–1988 E28 525e (or 528e in the US)