I think they are inter-changable. I put a Maximum Performance long travel kit in the rear of my 1999 SX years ago and it made a huge improvement in the ride. Maximum Performance is no longer around but their head shock guy started Pioneer Performance and they still sell the kit. If I remember correctly, when the longer shocks were installed, something on the transfer arm had to be changed. The below is from Pioneer Performance's web site.
SX, SRX REAR LONG TRAVEL SUSPENSION KIT
Greatly improve the ride of your sled without affecting the handling! We take your rear shocks, install new shafts, re-valve them, and change the center shock spring. When we’re done you have the same amount of rear travel as the SX-R & SXViper. The major difference is this kit is designed with more “set-in” on the rear, keeping the rear ride height at nearly stock level when sitting on the sled. The increased travel allows us to keep the spring rates lower, while the longer travel gives the shocks more time to react. This combination gives you a better (plusher) slow speed ride, improves the ability to go through the bumps at higher speed, and increases weight transfer. Send us both of your rear shocks and we install new factory parts. We send them back with all of the necessary parts and instructions for easy installation. Specify year, model, rider weight, and riding style when sending shocks in. After-market control rods are not necessary when installing this kit.
SRX – SX Long Kit '97-'99 SX, '98-'99 SRX:...$369.00
2000-2002 SRX:.....$355.00
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