The color call out on the exhaust is given as cockpit green( like British interior green). This doesn’t seem right, but I’m not having much luck finding out on the web. I’m sure that is operator error. If anyone knows the correct color, I would be grateful. Thanks, knox 
Soviet aircraft had some kind of ceramic coating inside of their afterburner sections that was green as well. I’m not sure if the J-79 was the same. But I can tell you when I was in 7th grade, I had a peek into an in-service F-4C afterburner, and the interior was a deep, oily, velvety black that stank of kerosine. How do I know it was velvety? Heh heh, damned kids touch everything! [:P]
Here’s a pic I took of the inside of a burner can on an RF-4C at Ramstein if it helps. More modern US engines have a flat white ceramic coating on the inside, but I think the old J79s had more of the XF-71 kind of color from what it looks like. The outside though would be more of an ALC111 (Magnesium) color.
Thank you so much for the replies and the picture. That is really helpful. Real G, too funny, but we sometimes do that as adults as well. . Thanks again. Now for some painting.
knox
My memory of F-4 tailpipes (I used to work at MDD) was that they were burnt metal color inside and out. To be sure, I just went to Google Images and looked at F-4 exhaust stacks.
The inside on anything other then brand new engines is quite dark burned metal. On the outside they vary a lot in darkness depending on time on engine. High time engines have a dark look as dark as insides. They have a very slight tint towards blue but that may be dependent on lighting.