Can I install cush drive on a older flh ? Is it anything more that the rear pulley on rubber mounts? Sorry if this seems like a stupid question to some , but I am here to learn.

What is the benifit of this cush drive?

 

What year is your bike?

 

Pretty sure the IDS was employed to mitigate the harmonics of the 6 speed transmission. HD made it OEM in '08, after making it available as an option for the '07. Not sure if there would be any benifit to this mod on your bike.

 

It likely won't fit, as axle sizes and tooth counts may not be compatible. The '07 fit a 1" axle while the '08 was 25mm, although that is only an issue with the bearing. U.S. sprockets were 66T while Japanese were 68T, so you would have some choice there, but most earlier bikes were 70T. Anyway, even if it did fit I doubt if you'd get much benefit from it, as this was a fix for clattering six-speeds and I never heard of a five-speed that clattered.

 

2002 Road King Clasic

 

The primary drive on your bike is different to the later models that have the rear cush drive. I've ridden my old FLHS for over 20 years and cannot imagine any benefit from fitting one.

It's benefit is for owners of the latest models, not us!