Well, like you, I was very curious about this transmission on a W111 3.5 Coupe. I asked the question in his thread but he never bothered to answer.
The W111 3.5 already had the enlarged tunnel so all manual equipped cars came with the side shift system (No ZF). Though the workshop manual specifies a 5 speed manual transmission was available for these cars (G76/27-A5), it seems none was ever built with it. It looks like the only manual transmission fitted on 3.5 W111 Coupes was the four speed G76/27-A one. Apparently, the G76/27-A5 was fitted on some W109 3.5 delivered to the German Government and to the German Diplomatic Services, not sure if any made it to the market. Later, it was fitted on some r107 350SL available on the market.
It seems there are two models of G76/27 A5 transmissions with different gear ratios. One has the same speed ratios as the four speed, with the addition of an overdrive 5th. The other one still has an overdrive 5th, but ratios are closer I believe. The first one can be duplicated by blending a G76/27-5 (5 speed transmission for 6 cylinder cars) and a G76/27-A (4 speed for 3.5 V8). I did it on my Coupe.
Original G76/27-A5 transmissions are extremely rare. Duplicating one uses exactly the same parts combination, the only difference is that it wasn't put together at the factory.
The pictures of W113 Savvy's car clearly show a G76/27-5 speed transmission. Not sure if it's an original G76/27-A5, a duplicated one, or simply a G76/27- 5 (for 6 cylinder cars) that was adapted to the M116 engine.
If it's an original one I don't think it was originally fitted on that car. If it was, this would be the first one I hear about, and I guess it should be mentioned on the data card. I guess any of these above mentioned options would have an incidence on the value of the car, hence a possible reluctance to answer my question. But on a purely technical point of view, there is no doubt the factory could have built a W111 3.5 Coupe with a G76/27-A5 transmission. May be it has. May be this is one of the potential very few. May be the only one! What a rare car that would be! I would definitely be interested in knowing, as this would contradict what is commonly believed by the few enthusiasts interested in the matter!
As mentioned above, the other option is that it's only a 6 cylinder G76/27-5 transmission that has been adapted to the M116 engine. Input shaft is shorter and spline pattern is different. But the 3.5 bell-housing fits. One could imagine the shorter input shaft was compensated my machining down the intermediary flange between the block and the bell-housing, and/or the bell-housing. The spline pattern issue can be addressed by using a BMW clutch disc which uses the same pattern, and is 240mm diameter like the 3.5 one.
Who knows...