Yeah I though the same thing, so I checked it out. And... sure enough, front and rear shafts are locked together when the t/c is in neutral. Don't make sense to me either. But as the Andrew's Sisters sang, "it's a fact man, it's a fact"
:frusty:
It's a fact, indeed. On a J-shift, like mine, the Neutral position is halfway between H4 and L4. So I assume the locking occurs when the TC goes into H4, and it doesn't undo between H4 and L4--the 'neutralness' is with respect to the TC input shaft as the TC goes from direct drive (H) to the reduction drive (L) only. For this reason, I'd tow it in H2, where at least the front shaft is decoupled. Then you don't worry about the TC, because it will be as normal for operation in H2. The TC doesn't know or care if the motive force is coming from the input shaft or the rear output shaft--it just locks them together. The reduction gear does not turn and neither does the front output.
So then the concern is only on the 5-speed which is in neutral, so the output shaft is spinning but not the input. I don't know the architecture of a car 5-speed with synchronizers; I've only been intimate with tractor transmissions which don't have synchronizers. There are three shafts in the 5-speed: the input shaft, which is fairly short and simple and is not equipped with any pump or slinger that I can see when I look at the EPD. It won't be turning and I wouldn't worry there. It's also higher than the output shaft, so I don't see how it can play much of a role in lubrication other than receiving it. The reverse shaft only turns in reverse, so its life will be the same, no worry there. The output shaft WILL be turning; it's a long busy shaft with a lot of stuff on it. It's looks to me as if it lubes itself, so I don't think its life would be any different in tow mode than in driven mode.
So I conclude that towing a 5-speed in H2 with the trans in neutral is fine. I would disconnect the D/S for a cross-country tow, just to be safe, but 100 miles at a time would not bother me a bit with the D/S engaged. I would not tow a 5-speed with the J-shift in N, only H2.
These comments do not apply if the TC is not a J-shift; I haven't looked at that.