libffi-devel question

[Costin Lixandru]

Hello guys,
I am looking for libffi-devel for an older system that does not have other
option (rhel6).
For unknown reasons the library is not on the Redhat web site anymore.

While I understand their reasons to not support it, we are having a very
hard time using some software that hasn't been updated in a very long time
in conjunction with Python3. Trying to install Python3 compiling from
scratch stops because of missing this library.

This libffi-devel would be very helpful and while I found the libffi in
lots of places, I could not find a trace of libffi-devel.
I am a casual programmer and I may ask a stupid question but by any chance,
could you please suggest where may I download it, or is there some
compiling option to turn the regular library into -devel?

Thanks so much in advance,
Costin