@subzali, don't hold me to it but I think the versions are FTM-400DR and FTM-400XDR, the 'X' revision being a change to a different GPS receiver chipset that improved the reception.
In general Yaesu radios have either an 'R' or an 'E' as their last character in the model to designate the Americas (or it might be even the standard global) with an 'R' or Europe with an 'E'. So the original version would I *think* have a FTM-400D on top and the newer one FTM-400XD like he's showing.
For example my FT-8800R just has "FT-8800" on top of it and you'd have to look at the serial number and model on the body to see "FT-8800R". Nic has a Euro FT-8800E that we made into a US version by changing the jumpers on the PCB.
A new FTM-400XDR is $590 now so it's probably a good deal in any case.