The exhaust port on the 1983-1988 models have a CO testing pipe on both sides of the engine. This is used to get quick access to the exhaust gas for CO test purposes. The pipes are capped on one side (with a blue rubber cap and clamp) and connect the the exhaust manifold on the other side. The connection on the manifold is a pipe-type of fitting. Different versions exist as follows:

MY 1983-1986: 928 111 149 03 for cylinders 1-4 (EU pass.side), and part number 928 111 150 00 for cylinders 5-8 (EU driver side).

MY 1987-1988: 928 111 149 05 for cylinders 1-4 (EU pass.side), and part number 928 111 150 01 for cylinders 5-8 (EU driver side).

Some pictures:

Cyl 1-4 1983-1986 model (928 111 149 03)

1983-1986 cyl 5-8 (928 111 150 00)

It seems that if you want to close the port on the manifold, the lug nut simply fits...

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Illustration 202-05 '86 has a total of 1 pipe lines, there is no mention for which cylinders. It APPEARS there is ONLY 1 TOTAL pipe line in this illustration....

Illustration 202-10 '86 has a total of 2 pipe lines - 1 per header. With a different part # for cylinders 1-4 and cylinders 5-8. For a TOTAL of 2 pipe lines for the engine.

Illustration 202-00 '87 has a total of 2 pipe lines - 1 per header. With a different part # for cylinders 1-4 and cylinders 5-8. For a TOTAL of 2 pipe lines for the engine.

DonT.