If you find one, there is a good write up in the last 2 LOCI magazines from 1800heap (Nick)covering the diff rebuild and this is also available on the forum as part of Nick's posts in the thread "Looking for Moths" . That reminds me I need to copy the relevant paragraphs across to the Technical Section!
Nick noted some incompatibility between crab manual and auto diff parts and there may be some other differences between the Ambassador and crab boxes. I think Tommy mentioned something several years ago but it may have referred to manual boxes? I assume the 2.0 L Ambassador auto used the higher ratio diff as well.