FWIW, I received the following reply to a query regarding applicability
of bosch 4 plugs to my 89 Westy:

From:   akademia@akademia.com (akademia.com)
To:     Vannpyre@aol.com
CC:     akademia@akademia.com

Hello from aKademia.com!

We have conducted a comprehensive search, and it seems that we were unable
to find Bosch +4 plugs for your vehicle. It seems as though Bosch has not
yet manufactured such plugs for your specific car.

We're sure more plugs will be made available in the coming months.

Thanks again for visiting us,
Susan B.
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