I like the badge bike look so checking to see if it would fit. thanks 

They do on the CT1 to CT2, I'd guess it would be the same on the DT series.

There's a slight difference between frames but i cant remember which way when swapping tanks--like early to later or visa versa. The difference is where the subframe is welded to the top tube. Its all do-able but there's something there where back of the tank sits to be careful of.

It might. I have a rat bike that's a 69 DT250 frame with a 72/73 DT250/RT360 tank on it. The seat comes down on top of the tank. The seats all beat up so i just use a piece of tube to dampen it and it works fine. The DT1 tank might be shorter and may yet work but the frames are definitely different.