Avoided A Near Major Accident - Need Differential?

I'm not sure I see how the diff had much effect - you were probably not on the gas once you started the evasive maneuver.

yea, i agree with hissin.. my 92 was kinda shakey like that.. it would roll itself around all it wanted.. i'd look into sway bars, spring.. whatever i could to stiffen the sucker up

Doubt it would have made a difference. These things are really @ss light so its kind of the nature of the beast. Possibly IRS(if not for just the weight itself) and/or a battery in the back may help prevent such a thing slightly. Good tires and suspension goes a long way....
Kevin

I'd note that it is almost intuitive to oversteer - no matter what you're steering set-up is (you have so much adrenalin going through you that most folks overcorrect even if they were steering a barge with door knob).
It's a learned technique to not oversteer (I use shuffle steering when needing to fight these natural tendencies). Driving with one hand on the wheel and another grabbing gears makes it that much worse.

Kevin has some good ideas - these cars plow and (mine atleast) oversteers. That's a nasty combo. I've had the pleasure of driving a car with 51/49 weight distribution and when it whipped around (no driver input given - it was left to spin), it went straight down the icy road.