Thanks again guys for your help, I have the V5 now and it was registered in the UK in 1993, the frame and engine numbers match the V5 and are both 1R6000***.

Could well be an import then.

1R6 is model prefix of european market DT400 of 1977 and 1978 vintage.

With the "000" at the start of the suffix, it's very likely a 1977 model. 

It certainly could be an import, no matter where it came from it was a model originally intended for outside the USA.

One "feature" some of the earlier bikes had that appear to have come through the Netherlands distributor was the VIN stampings started and ended with a * symbol....  example *CT2-400134*

I have never seen that * used in other parts of the world...  not sure if it was always used or just on the early bikes.

* fore and aft of the VIN might have been an EEC/EU requirement, but I'm not absolutely certain of this.

Steve Bateman in Dorset was quite a big importer of bikes from the US at the time your bike was first registered in the UK - I got a GS1000 from him and Gr8auntiepat got a FZX700 (Fazer, aka Baby V-Max).

Thanks again
mine does not have the * just 000 followed by 3 numbers, it is registered as a 1977 model, has mph clocks but who knows what has been changed during its life, looks like it’s had a previous ‘previous’ restoration some years ago. All in all it’s a decent bike and I’m looking forward to getting out on it as soon as I have given it a overhaul and new brake shoes.