The NI Community Forums (forums.ni.com) have an active “Legacy Software” section where engineers still answer 8.5.1 questions daily. Good luck, and keep your legacy systems running smoothly.
: The most reliable way is through the NI LabVIEW Runtime Download page . You will need to log in and may need an active service agreement to access older archived versions. labview runtime engine 85 1 download 2021