Please note that most Adelard developed plugins written for previous versions of ASCE are bundled with later versions. So ASCE 4.1 includes plugins from ASCE 4.0 and 3.5, and ASCE 4.0 includes plugins for ASCE 3.5. Unless an updated version is available, you do not need to download them as they are already included.
Some experimental/beta plugins were developed for ASCE 3.5. Most of these have been updated formally issued as part of ASCE version 4, and will be maintained as part of the ASCE version 4 plugin set.
However customers that wish to run these older versions in ASCE 3.5 may contact asce_support@adelard.com for availability, with the understanding that these plugins are not officially released and are unsupported.