I am thinking of replacing my mast with one slightly taller
I have sourced (new) the appropriate section and length in sydney
But would like it anodised as per the original but not sure if its still possible to have it done ?
Any suggestions ?

Finding an anodiser with a suitable length tank might be difficult. It was for me some years back when I designed and built a hi tech., 14ft racing catamaran!

As an alternative you could look at using Nyalic www.nyalic.co.nz . I rebuilt my mast and boom and sanded off the paint and the corrosion around the many scratches and abrasions that is typical of a painted mast. I then applied the Nyalic which flows and looks like water but it gets into the pores and surface of aluminium. I was told it is like a cold anodising treatment and was developed years ago for the US space program.
I did this 9 years ago and the mast has no corrosion or oxidisation whatsoever. I don't have black or chalky paint on my hands or legs after a climb up my mast these days for a rig check. I bought 500mls and still have about 200ml left as it goes a long way. I have since seen it used on an aluminium charter boat hull, it looked really good too.
You may have to import it from New Zealand as I had to but There may be an Australian agent for it these days.
Wayne

Theres another alternative. Leave it bare.

The surface will oxidize and form a protective layer. I re-rigged my boat 2 years ago and was going to either anodize or paint the aluminium sections that looked terrible. My rigger suggested sand the AL smooth and leave it bare so I though I'd try it (since its free) and painting or anodizing didn't seem to protect the critical parts anyway.

2 years later its the same as it was then.

Thanks for all your responses i will let you all know how it turns out