Rectifier For Cary SLP 05

I am currently using a Mullard GZ34 and have been for a while now. on a Cary SLP 05 preamp.

i am shopping for some back up replacements.
Will a Brimar 5R4GY be a drop in replacement and if so, what sort of sound does it have compared to the Mullard GZ34?
The 5R4GY is not a drop in replacement for the 5AR4/GZ34 as they have different electrical properties.  As to can you use a 5R4GR tube in your Cary, you will need to ask Cary.  The Mullard GZ34 is considered one of the best rectifier tubes you can buy and they last forever. 
Personally; there are only two 5AR4 iterations, that I would consider against the Mullard(Blackburn) GZ34.      Both, from Philips:    and:    No connection to either reference.
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@testpilot here's hoping it does last forever.
@rodman99999 how do the Phillips GZ34's sound vis-a-vis the Mullard?
@tvad I am checking with Cary on both the Brimar and the Mullard GZ37 nut as it is the weekend I thought I may get a quicker response here from folk who may have tried one.
Slightly less warm/better definition(realism), but- still with an extended life expectancy(20K to 30K hours).      There are also a few differing iterations, within their metal base, GZ34s, that will vary slightly in presentation.      I prefer the tall bottle, 5R4GYS.      You may find a change from the Blackburn Mullard, a sideways move.      I’d never dissuade one, from experimenting, though.      It’s all about ones own aural palate and system, in their listening room.
Be sure to use the original British-made GZ34. The commonly available (and cheap) Mullard's are made-in-Russia knock-offs! No good! Real Mullard GZ34's have been out of production for decades. Ditto for USA and Japanese production. These are both 5AR4's. And are far better than today's Russian or Slovakian (JJ) types. Real British Mullard GZ34's will cost about $100 - $200. USA and Japanese 5AR4's $50 - $100.
They don't last forever! The British, US and Japanese versions are good for about 5,000 hours use. More if you are lucky! One of mine in a 1963 Heathkit AA100 integrated amp died after many years of use. I was the second owner.
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I use one of those gigantic 274b rectifiers because it's simply so cool looking, and it seems to work well...the "preferred" version. Might not fit in some amps.
Just an update so other folk will know for the future. Cary says it is electrically the same but will not fit because of the size.
Also, they don't recommend a directly heated rectifier 5R4 or 5U4 on the SLP-05. " Use indirectly heated tubes like the 5AR4, 5V4/GZ34, CV1377, GZ32, GZ33, CV729."
In any case, the reply came too late as the seller couldn't wait and sold the Brimar. Not that it mattered in the end.
i have a new slp-05 on the way and would like to know if the latest rectifier and 6NS7 tubes sound OK once burned in.  Thanks.