[Rick Parker]

The yellowish tint that is present on the gear is the gear marking compond that is used on the teeth to check the gear mesh pattern, it allows for a visual refrence. It makes things look pretty messy.They may have attempted to wipe it off or clean with solvent prior to shipment and any residue will have left the yellow tint. If there is any "heavy rust" certainly that would be reason for concern. Speaking in general terms most of the vendors sell there "center sections"with used cases (unless new is specifically requested) new bearings, new gears, new or used ring gear carrier (traction lock, or Detroit Locker or open). On the traction lock carrier one area to pay very close attention to is the area under the ring gear bolts that secure the hat section. The machined area near the bolt heads (to the inside) can develop cracks or be machined to thin and it will fail from the internal spring pressure exerted. Several vendors make new 9" castings Curry, Strange, Mark Williams and others. In there worst form the Ford 9" is quite strong, until Strange Co & Mark Miller developed purpose designed & built rear ends, these were the main stay for the fuel dragsters and are still used in all but the most brutal classes. It is used exclusively in the Cup cars.
Rick