I have a 1991 Bayliner ceria sunbridge 2655 mercruiser alpha 1 outdrive . the boat slid off the trailer on a concrete boat ramp . so far I see is the lower unit casing broken , oil drained out . the boat has 842 hours on it . should I find a used casing and transfer my gears to it or buy a new lower unit ? also should I be looking for other damage to the outdrive or hull ? thank you for looking .