In the past, shortly after OFP was released, pictures seen in forums of C-130s in OFP were fakes. Now, however, C130s are making their way into OFP.
The first one available is that of addon maker Adammo. Way back in May 2002, he was still working on the textures and details. In September 2002, Adammo released versions 1 and 1A of his C-130 to the public, available at reliable OFP addon download sites everywhere.
Many other OFP addon makers may still be working on modeling a C-130. An example of a work in progress can be found on this page on OFPN's Operation Vietnam site. And, now with BIS beginning to provide their Oxygen program to selected mod and addon makers, these might be coming out in the near future.
In June 2002, OFP addon maker Konyak, shocked everyone on this BIS OFP forum thread, when he revealed his work-in-progress development of a Soviet AN-124 Condor (Antonov) transport jet. He's still got a long way to go, says Konyak, but this is certainly something to look forward to.
That's one big bird!