Bosch Spark Plug ID help

[RLJ]

Bosch XR2CS

These little darlings are used in my dual plugged heads.
Normal plug in the stock position and this plug in the bottom hole.

What does this plug fit? (Besides the bottom plug hole in my hot rod motor heads.)

An airplane, old tractor, or what?

Is it a plug size that has a heat range, or is there just one heat for this size?

Also any cross over numbers to other brands.


Randy Jones
1971 911

[nick-moss]

There is a cross reference chart here

It seems to be used in a Susuki GSXR 750 and at True Choice a reference to "PORSCHE 6CYL RSR"