There were two versions while under the RACAL name -501 and -503. The 503 is newer and will accept 8.? version firmware whereas the 501 has a different lower numbered revision. They made a few RF antenna port changes and other smaller improvements in the -503.
As for the Thales, I don't know. I would assume that things have been improved over time but as of right now the the current firmware updater package works for the latest product all the way down to the old 501 series. It will auto sense and adjust to whatever revision of radio it's trying to update. So, basically it doesn't look like there is much difference between the RACAL and Thales models.
I have a racal (thales??) prc6841HBRV, batteries are shot, have ac charger, are there batteries other than $200 ones listed, or a ni-cad rechargable cell holder? I am a Ham and want to try it out.
Thanks