Installed Clear Tops over weekend and like them enough to order another quad to stash for future use. (did that before posting here, sorry fellas) They are RCA made Conn labeled electric organ stock and the four I received are all very tight match, dead quiet and CHEAP. To my ear they are different and every bit as likeable as the Mullards, but with a quad costing $350 less, well, it's no contest.
Here is the listing URL, he has a bunch of other tubes (lots of RCA relabels and other 12AU7s):
Or here is his seller page if listing expires:
Doubtless someone here has bought from this seller, but he's new to me and ebay can be a bit sketchy. (he seems to sell electric organ vacuum tubes and baseball cards - it's eBay, go figure??)
Moved the Mullards to the driver slots in my M125's and the bright RCA sound in preamp feeding the Mullards with their sweet mids is pretty much delightful in my rig. Really happy.