No, it's 12-Volt phantom powered. It could be modified for 48-Volt phantom powering if necessary--although 12-Volt phantom is twice as power-efficient (4 mA x 48 V = 192 mW; 8 mA x 12 V = 96 mW).
I have one of these from the very first batch ever made. I've used it hundreds of times, including with speech cardioid capsules for documentary recording, and once even with supercardioid capsules for a special situation. I intend to keep that microphone for the rest of my life, however long or short that may prove to be.
Mine's from 1977, though, so assuming that the capsules in the auction are of a similar age, there's a problem. Normally I would very strongly advise anyone to send them back to the factory for checkup and any needed repair, unless you knew for a fact that they'd already been serviced fairly recently (the factory can tell you if you give them the serial numbers). But such service will surely be expensive. Schoeps assesses flat-rate service fees based on the age of the item(s); equipment that's >20 years old is considered "vintage" and falls into their highest-cost tier--and this equipment is over 40 years old.
You might wish to send the amplifier back as well, since there have been circuit updates since then, mostly to help prevent RFI (although this model will never have the degree of "RF-proof-ness" that a CMC 6, CMC 1 or CMIT has). But definitely definitely definitely write to mailbox@schoeps.de before doing so! They may no longer maintain this model, considering its age and the fact that another model (the MSTC 6) has replaced it. (And no, it can't be converted in a cost-effective way.)
Going one level deeper in--the two MK 4 capsules that come with an MSTC are always a matched pair, which makes sense for a near-coincident recording method. However, if either capsule were to require much more than simple cleaning and "small parts replaced" as they call it, it might well have to be completely rebuilt due to its age. Then you would presumably want to have both capsules rebuilt so that their specifications would match. And Schoeps might well decline to perform such a repair, since it would almost certainly cost more than 30% the cost of a new pair of capsules (30% of replacement cost is their threshold of calling a repair "economically unviable"). So please consider that.
BUT if you do find a way around these problems, I think you would like the MSTC very much.
--best regards
P.S.: muj, there was indeed a T-powered version of the MSTC called the MSTC 4--, now discontinued. Since T-powering was mainly a film-and-video-sound thing, and ORTF stereo recording isn't strictly mono compatible, not a lot of that particular model was ever sold; film and video people prefer M/S, which gives the post-production people more options, plus for booming a mike, the preference would be to put just the capsules on the end of the boom, and to use active cables to connect them to their amplifiers. (By the way, MSTC amplifiers unfortunately don't support Colette active accessories.)
[edited later to add:] Schoeps has upgraded the MSTC so that it is built now around, essentially, a pair of CMC 1 amplifiers. In the process, they changed the contact plate for attaching the capsules so that the microphone now does allow Colette active accessories to be used. That may not be the most visually elegant arrangement, but it could certainly be useful for someone some day.