Thanks all for your help.
I got in touch with Bob (Precision Proformance), and purchased the master brake cylinder from him.
http://precisionproformance.com/bc2005.phpBob did confirm that it's a GM Master as per some of the previous advice. For prosperity I like to know where "other" make parts used on my Pantera come from.
Whilst I could of gotten it a bit cheaper elsewhere, Bob was helpful over the phone, and seeing as this is the first time I'm replacing the master brake cylinder and the fact that I'm in Australia it made sense to by from Bob just in case there are any issues that arise whilst replacing it.
Plus I'm it taking for granted that Precision Proformance are a trusted Pantera parts retailer and it gives me more confidence buying from overseas.
Bob also assured me that this is a "new" unit not "remanufactured" as by Cardone's.
http://www.oreillyauto.com/sit..._-1&keyword=10-2058+I've still got the booster in, as the pantera is drivable. It just leeks back into the reservoir.
Once out I'll take some pictures with the brake master cylinder out for prosperity. I should get the replacement in about 8-10 days.
Thanks all for your help.