C10 ThinOS Firmware Needed

Hello,

Have inherited a client with a few legacy C10LE Wyse terminals and need to update the firmware on them to, at least, 8.3_109 for what I believe to be a requirement to use in a Server 2016 environment.  Existing units are currently using Firmware of: 7.1_122 and 8.0_210.  Have located Dell Article SLN289285 which indicates the update progression of Major Firmware releases.  I understand these devices are no longer officially supported but the Firmware files for them must exist somewhere.  Where can legacy firmware files be downloaded/acquired?  A call to Dell Support directed me to this forum for the support for these (C10LE) devices.  Thanks in advance to all!