Source for open differential?

[artdutra04]

Does anyone have a source for a relatively small, light-weight, open differential for under $100-$200 each (we'll need two)?

Software will not work; and it absolutely has to be an open mechanical differential. The ones on SDP/SI are too small and too expensive, and most of the cheap Go Kart ones are too large and too heavy. There looked like there was a promising one in an older thread, but the link was dead.

// If there aren't any readily available, we'll probably end up having to mill our own differential housing.