I didn't know about the 3/400 series.
One nice thing about the migration to SPARC is I was able to personally buy a retired 3/75 from the local Sun field office as a teen. Unix and megapixel display for a fraction of what assembling that with a PC would've cost. :)
The 3/80 was also notable for using the Sparcstation expansion bus called 'SBus', which Sun used to claim SBus was an 'architecture neutral' expansion bus and tried to position it as a competitor to PCI (for a very short period of time). I went to a Sun SBus hardware design class at one point...it was a nifty design but clearly wasn't getting market traction outside Sun.