440's (out of production?) and now improved 444's are heaps better and your Valkyrie ones should be adjustable for preload with the top threaded adjustment without steps so you have to carefully ensure you have them at the same number of turns from minimum preload.
The Valkyrie one you have should fit the Rocket as the same 444 versions fit both too.
Progressive Cruiser Shocks 13.0" Chrome 444-4221C | eBay
Adjusting progressive 440 shocks
New Progressive 440 12.5 Black Shocks Honda Valkyrie | eBay
$645.95 Progressive 440 IAS Heavy Duty Shocks 12 Valkyrie #809614
440 FEATURES
- High-pressure Gas, Adjustable-charged for consistent damping performance
- Patented Inertia Active System (IAS) damping for unsurpassed handling and comfort
- Top mount threaded preload adjuster allows for fine tuning with a simple twist of the cap
- Feature two independent rebound damping circuits
- Available with chromed billet aluminum end caps with chrome springs or black anodized end caps with powder coated black springs
- Inertia valve determines whether the soft (wheel) circuit or the firm (chassis) circuit is utilized to optimize both handling and comfort automatically
- All three damping circuits, compression, as well as soft and firm rebound are also velocity sensitive
- TUV approved
- Heavy Duty applications are recommended for bikes that are operated at or near the manufacturers maximum load rating over 50% of the time
- Length: 12"
- Sold in pairs
- Fits the following Honda models:
- GL1500 VALKYRIE 1997-2003 (note: standard shock for 99-01 Interstate models)
- VTX1300 2003-2009
- VTX1800 2002-2008 (note: 05-08 C and F models require two rear cushion bolts, Honda OEM# 52452-MCH-000)
- Fits the following Kawasaki models:
- VULCAN 1500 CLASSIC 1996-2008
- VULCAN 1500 DRIFTER 1999-2005
- VULCAN 1500 NOMAD 1998-2004
- Please Note: The image displayed is representative of the item, but may vary depending on your specific model.
There have been different factory rear shock spring rates on some Rocket models - some sources say harsher, presumably heavier springs on early ones and softer on Roadsters and Tourings. Whatever, they are all woeful compared to quality aftermarket ones with the correct spring rate for you weight/% usage with pillion / luggage etc.