Are All Mullards Created Equal?

Thank you for your responses, and happy New Year!

Jgiacalo,
You quack me up.

The straight man's answer is absolutely not. There are differences in Mullards from one plant to another from different vintages and of course design such as long vs short plate, halo getter vs D getter, black plate vs grey plate (IIRC?) and of course from type to type within a family such as the 6922 VS the CV2943 vs CV2942.
I find Brente Jesse while being a respected honest dealer does a diservice to Mullards describing them as if you were wearing a tweed jacket or something ike that. He says that about every Mullard regardless of type.
If you want a detailed discussion of a particular tube I would be as specific as possible and post my question over on Audio Asylum Tubes Asylum. you can also do a search first that might answer your question.
Even Mallards aren't all the same at least to them. To you they may look alike.

The Mullard, or Wild duck (Anas platyrhynchos[1]), probably the best-known and most recognizable of all ducks, is a dabbling duck which breeds throughout the temperate and sub-tropical Americas, Europe, Asia, New Zealand (where it is currently the most common duck species), and Australia.

The male birds have a bright green head, while the female's is light brown. The mullard lives in wetlands, eats water plants, and is gregarious. It is also migratory. The mallard is the ancestor of all domestic ducks, and can interbreed with other species of genus Anas.[2] This interbreeding is causing rarer species of ducks to become genetically diluted.

The Blackburn Plant 5AR4/GZ34/CV1377(especially 1958-62, F31 series) = #1(ie: http://cgi.ebay.com/LOOK-NOS-NIB-f31-Fat-Base-Mullard-GZ34-5AR4-/360331594538?pt=LH_DefaultDomain_0&hash=item53e56fcb2a)

I believe the 5AR4s from the 50s to early 60s, built in England and Holland, are most desirable. Fat base, brown base, and metal base perhaps more so. These will be at a premium, but supposedly, they are indestructible.

There is a web site I stumbled upon that had some opinions on all sorts of different tubes. I purchased some Mullard 6922's from the site. I think it is Brent Jesse Recording or something like that. I don't know if he reviews this specific tube but it might help.