did exactly this and no tail light dimming and wow they are bright, worked a treat, thanks skydancer, recommend to anyone.

Ok, I'm back,

Man, I sure am busy this time of year!!  I finally received the Bikemaster diode kit Mark mentioned earlier in the thread. It works great too. Only difference is you don't have to run a long wire from P terminal (flasher relay) to the dark brown wire in the headlight bucket. So if you don't want to spend the extra $12.00 or wait for the diode kit just run the long wire. Doesn't take long to do. You will still need to add bullet connectors to the diode and run your ground wire. I just kept my ground wire that i ran into the black 3 wire connector and used it. See pictures. If you really want to make it perfect then use a black wire for the ground. I made a green wire as i have a ton of green wire laying around. You can see the diode connected on the left side in the headlight bucket. 






This set up works so good i decided to leave it on the 71 DT1 250. Anyone riding these bikes would benifit from this as there brighter, faster and more precise in blinking. In the video below you cab see how bright they are however once the color lenses are installed there perfect as far as i am concerned. 

youtube.com/shorts/zl8KZ0dKRw4?feature=share


Still working on the dimming tail light and brake light issue. Nothing so far has come up defective or bad  as mentioned in the earlier thread and my conclusion keeps going back to the battery as the only problem? If you run this LED set up your problem is solved. 

But this still doesn't explain why some bikes have the issue and some still don't? 



 

I would say you can make your own diode Y for less than a dollar but all the local places like Radio Shack and Fry's seem to be gone. I still have some old resistors and diodes lying around but most people probably don't.

Thanks for posting your results!