Correct, we offer the SHD and XHD version, the SHD version is a single row chain that is a performance upgrade, the XHD is a severe duty chain for drag racing 2 step limiters etc.
On Gasoline 100,000+ miles, on e85 without the e85 strip option about every 10k miles (or sooner depending upon how rich your application runs), this is due to the chemicals found ine85 fuels that get past the piston rings and into the oil, this chemical softens the plastic guides to the point of failure if not kept in check.