Yea, that's seen a bit of water. Going to restore the ballast?

After a thorough test I'll clean the rust off & blast it over with some cheap radiator paint, I refuse to spend too much time refurbishing ballasts, no one sees them anyway

Agree Adam as long as they work!

Will be a similar thing to what I did to this, which admittedly looks pretty good! I'm just not bothering with labels and exact colour matching. Will probably try to find some better paint though, the white I used on that one was sold as radiator paint but I don't think it is as it softens with heat :/

Haha, well, you see them if you open the fitting! To be honest, the main reason I started restoring some of the ballasts I had is that not only did I want to stop the rust and keep them working, on some such as the 2x 2' 40w, there are 8 terminals - 4 either end. It's not really very easy to work out the wiring diagram later on if the label is lost. So, I re-created them and decided if I was going to spend time doing it, I'd make them as accurate as possible. I now not only know what they are, I know how to wire them as well.

I drew the wiring diagram on the Transtar ballast with a marker lol

Must have had been out of use for a fair old time.