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The CR10L as you have found out, is also a 727 converter.
I have a ATC-PRO-KING catalog in front of me, and the proper converter for the 225 or 318 is their part number CR8L for the low stall and CR8H for the higher stall. AZ's cataloging on converters is wrong in so many places it's unbelievable! They have no listing for the 318/904 period from what I can find, only the 727.
Good luck on the latest transmission and converter. If I can be of any further help to you, drop me a P.M.