Does anyone have the part number for a 1975 DT175b turn signal relay?  Do you know a vendor that has one?

 Thanks in advance.

 

If you want to rigidly stick to original equipment, then the part number is 438-83350-62 and I have attached a photo below. However, any style of 6v flasher relay will do the job, so long as the wattage of the indicator bulbs matches closely to the numbers on the side of the relay.

If you go for a modern relay, you only need the two pin type and the brown wire goes to the terminal marked X and the brown/white to that marked L.

 

Here's another option.  I bought one and it is working well for me.