From the Q&A at http://lci1.com/index.php?option=com_content&view=article&id=274:tri-glide-faq&catid=34:products .....
Q. Is the air spring and shock absorber an off the shelf item?
A. Either Goodyear or Firestone makes the air springs and are standard air springs found in most of their industrial catalogs. Either Monroe or Sachs Automotive Co makes the shock absorbers for Trailair. Both companies use standard shock components but both have special internal valving suited specifically for the needs of Trailair. Suitable replacements may be obtained through authorized Trailair dealers or directly from Trailair.
OOOPS. Sorry for the double post, but couldn't find a DELETE on the edit menu????