DC, In this case, the answer is "steam pipe"...
I thought MX250's summation of the models (and their fuel tanks) was correct, but I'm still to get my head around the exact differences between RT2s and RT3s (and DT2 vs DT3s) - everytime I find someone who insists on a particular thing, I find someone else who is just as insistant on the opposite.
I think there are two main reasons for this:
1. Yamaha made lots of rolling changes so a late RT2 will have some of the RT3 updates (for example).
2. The
xT3s were more a marketing/cosmetic thing (rather than any real mechanical changes), and consequently a lot of documentation considers them to be the same bike.
As my interest in these bikes is more about racing them that nut-and-bolt resto, I've not needed to know the train-spotter stuff.