They were made in 2 versions, 1meg flash or 2meg flash.
If it's the 2meg version, use rigged hevet800/1000 firmware.
The 1meg version uses hevet500 firmware.
Pclinkv5.5 can save/upload firmware to the receiver.
The pclink password is loadbin, then hit the pickup button
to save the receiver firmware to your pc. I never tried it with
the 1meg flash version though.You will be able to tell the size
that way, or pop the cover and get the number off the flash
chip itself. It will be something like 29lv800 or 29lv160.
The 160 is the 2meg chip.