2001 Suburban K1500 rear end

Blown... Pretty well completely.
I got nudged, sitting in the line at a light last week. Got out, saw
there was no damage, waved the idiot off. When I got back in, the light
had changed, traffic had cleared in front, and I started up in a hurry.
Pulled into Drive and hit the gas. One rear wheel (2W-Hi) spun briefly
on damp pavement, then when it bit - Bang! No traction, no motion. I put
it into 4WD and limped it home on the front wheels, then had it towed to
an independent shop.
They confirmed that I had broken spider gear(s), with damage to just
about everything in the case, and referred me to their transmission and
gear shop.
The tranny guy is telling me the stock rear end is weak and frequently
fails if mildly abused like this, and recommends a tougher aftermarket
rear end.
Is anyone familiar with this problem? Any suggestions as to what level
at GM I should try to take up the case for them to cover it? (58k miles
and over 36 months, of course.)
Right now, they've cleared out the broken bits and refilled the case
with oil, so I could drive it home and park it, until I can figure out
what to do - and come up with the $1800 he estimates... Think it's safe
to drive it on the front end alone, for a while?

Dave