Tru64-Digital Unix

Hi
I need to install Samba on a Tru64/Digital Unix v4.0F,
but the only package I can find for Tru64 is for
version 5.1. Can I install this one on version 4.0F?
(I mean, is it backward-compatible?)
If not, would I need to compile it from source, and
does samba support this OS? (I have no idea if this
machine has gcc, I'll have to find that out)
Thanks!

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