I have X10R3 and X10R4 archives.
I have found it somewhere in google some years ago, I do not remember
now where, probably MIT or so. If it is allowed to upload it I can
upload it to TUHS.
But perhaps they are still available .
I've just run through a quite search of X[1 10]R[1 3] and X10R[3 4] seems to
be the only members of that vintage. One fragment on google said that that
was because it was the first example of the code to be released outside of
MIT.