"convert your open differential to limited slip easily and without pulling the ring and pinion"

http://www.powertrax.com

anyone install one of these? what kind of $ do they run?

They run about $400, available for most applications (except 7 1/4 ).
Looks like an easy installation, but I haven't tried one yet. Sometimes you can find new SG units for the same price, or less. The advantage for these is the "drop-in" design, no gear setup to worry about.

_________________
O==\=/==O

"A mechanic is Somebody."
- Jim Preston

yeah, they look pretty cool, especially for the fact that they can be put in without having to rebuild the rear, i guess they are only for C-clip type axles though, as there isn't a style for the 8 3/4 style...

Actually, Powertrax makes a drop-in locker (Lockright) for 8 3/4 cases.
It's even cheaper ($300) than the limited slip unit and replaces the spiders just like the other ones.
You just have to live with the ratchet noise .

_________________
O==\=/==O

"A mechanic is Somebody."
- Jim Preston