what should i expect to pay 8 3/4 chunk?

I've got a 3.55 Ring and Pinion in my garage that came out of a 742 carrier if you're interested and can find a bare carrier.

The biggest differences are the driveshaft u-joint sizes. The 741 uses the small one, and the 742 and 489 use the larger size. The 489 also uses a clutch type suregrip, while the 742 is a cone type that isn't rebuildable.

Hope that helps some!

Mike