If I recall, Anlun made frames, forks, bars and components for a lot of companies in the 80's, most famously for Haro. Redline used them for some of their stuff too not sure of other companies.
I remember seeing adverts for anlun stems that were the same as Haro models eexcept for the top part of the stem. Same as Wellgo do for pedals now, just brand up their part with another companies name. I'd imagine all the different companies pivotal seats/posts are all made in the same factory too.