Thank you all for all the images and offer of a modem.
After studying all the images, it would appear all the modems from 2012 to 2015 use the same description and part numbers printed on the label attached to the ECI modems! Jsamuel's thread and the OpenWRT wiki both indicate the only way to identify the version is to open up the case and inspect the markings on the Lantiq SoC.
I did find an OpenWRT changeset that acknowledged the existence of the v2 modem in April 2014.
I was hoping someone had installed Jsamuel's OpenWRT CC to an early production v2 modem, and may be able to help.
fyi, LEDE 17.01.4 runs fine in bridge mode on v1 modem, but the LAN1 and LAN2 ports are transposed on the v1 modem when displayed in LuCI.
https://openwrt.org/toh/bt/vg3503jThe line stats presented in LuCI graphical interface when using Jsamuel's OpenWRT 15 image, is still superior to what is offered in LEDE 17/OpenWRT 18.