there are a few seperate issues here.
1) the original urei 1176 had many revisions. from the first rev A to the rev F all used a bridging t-pad into a UTC o-12 wired as a 500:200 stepdown as the input transformer. starting with rev G, the input transformer was replaced with the cheaper opamp input. ALL revisions of the urei 1176 use an output transformer. in the rev A thru the rev E, they used a special output transformer with a tertiary feedback winding that was needed for the class A output circuit. starting with the rev F, they changed the output circuit to class A/B, and changed the output transformer. a few revisions later the output transformer was changed to be PCB mount instead of flying lead mount, and they switched manufacturers.
see here for more info:
http://www.uaudio.com/webzine/2003/august/index4.html
as an aside, i'm not totally sure that these divisions were so hard and fast. i think that it was probably possible to order a rev G with an input transformer or a rev F without or any number of variations. front panel color was also an option, so distinctions like "blackface" or "silverface" are more or less irrelevant.
2) the purple audio MC76 and MC77 have always used a t-pad into a real UTC o-12 wired as a 500:200 stepdown input transformer. a while ago the manufacturer of the original bridged t-pad stopped making this part. purple was able to replace the bridging t-pad, which uses a 2 deck pot and a pair of resistors, with a non-bridging t-pad, which uses a 3 deck pot. the output transformer for the MC76 was originally manufactured by reichenbach (not what is now bauer, or cinemag). when they went out of business, purple started getting them made by cinemag. the MC76 and MC77 use the same class A output circuit as the rev D or E urei units.
3) the UA 1176 reissue originally used the same bridging t-pad into a UTC o-12 as the urei and the purple. when the t-pad supply dried up, they redesigned the input circuitry to use an off the shelf cinemag 15k:15k transformer feeding an ordinary pot. their output transformer is a reproduction of the original, not made by cinemag, with the tertiary winding, and is not available for purchase by the general public, except as a part through UA. the UA 1176 uses the same class A output circuit as the rev D or E urei units.
4) the gyraf g1176 has the option of either using an opamp input circuit, which would be the same as the rev G urei units, or a transformer feeding a pot, which would be the similar to the current UA 1176 reissues. the output stage of the gyraf version is class A/B like the rev F and later urei versions, so it can use a regular line output transformer without the tertiary winding. jakob originally specified a lundahl output transformer that he felt matched the sound of his urei unit. mnats newer boards also allow for the use of OEP transformers, on the input and output.
i hope this clears things up, at least somewhat. i must point out that with all of these revisions, of the original and the other manufacturer's versions, there is a very wide range of sounds. if you want to roll your own, your choices now are to get the gyraf version, which can sound like the class A/B ureis, or the purple version, which can sound like the class A ureis. other component choices, such as caps, transformers, active components, etc, will also have a large effect on the sound of the finished unit.
ed