There's probability that SunRace derailleurs are Microshift - Microshift's primary business volume is production for other companies.
I've seen their derailleurs pop-up in other companies catalogs...brand-name and non-brand name alike at Interbike - minus the label.
And each company is able to specify "style" modifcations as part of their order.
=8-)
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5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life