The #4 and the '91 are very similar, but there are a few different '91 cuts around. I doubt one is around anymore, or at least the old timers I know out here in the CO jam scene haven't seen it in a while. I've also been told (From multiple reliable sources, but DQMOT) that another cut with the '91 moniker has been reworked into some diesel lineage by a Cali crew and that looks like the cut you have. It does the Bay Area/LA loop every year, usually clones are around this time of year since it's not a very good outdoor strain...I've also seen some CC "chem" that looked alot like that, but who knows...the two cuts i've seen weren't very big yielders.
D and Sis are very similar, I've grown both alot and have lots of personal experience, and it's always a battle between which one yields more. but each is always one of the bigger yielders...Not as big of calyxes, still lots of calyxes though. Very dense and VERY white buds. I've only seen the D get deep orange hairs and amber at around 11-12 weeks, Sis is a little earlier.
