Almost correct. The first laser printers were not the Dover but SLOT by Gary Starkweather at PARC, which was made on top of a 3600 (much faster engine) in the very early 70s, and its connection to the Ethernet EARS a little later (by Ron Rider using an Alto as the server computer).

PARC really wasn't an R&D center for Xerox copiers (this stayed in Rochester), and Gary was a great engineer who could do the work of making a laser and its optics and scanner work with a standard copying engine pretty much by himself.