Just looked at the AVO site.. they have a 9" damper single adjustable coil over damper listed with a 2.25" spring which is available in 3", 4" or 5" (ie. short lenths). That said the 5" is recommended for the 9" casing.

Given that they are the supplier of the non coil over Rutherford AVO dampers they can probably replicate the build in a coil over casing.. then you only have the problem about strengthening the suspension hoop to act at the main suspension device... rather than the leaf springs.... which having look at it would need at least front and rear triangulation onto the chassis somehow or possibly joining up with the roll-over-hoop if you have one (BTW, this is also blue book allowable) so does not contravene MSA regulations.

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