1:10 or 1:12 scale project wanted...

[Patrick]

***RC***, I don't think having any oil in the centre diff should cause it to lock up while coasting like you said, since if your coasting then the front and back wheels should be spinning the same speed as each other and the gears in the diff should only be spinning when the two outputs (shaft to front diff, and shaft to rear diff) are spinning at different speeds. If the gears inside the centre diff lock up it would just be like having a spool or a solid shaft (front and back diffs will get the same power), but it won't stop the car from rolling.