Paul There is the Mercedes coupler i talked to you before ,they have several models on EBAY and very cheap,you can design the shaft without spline but only an adapted flange cup to meet the coupler and the flexwheel as safety in case the rubber fail.I do have an idea of the shaft design with this Mercedes coupler.Ths one is for the 550 model http://cgi.ebay.com/ebaymotors/Mercedes-W116-450SE-W124-300D-T-300TD-T-Flex-Disc-Kit-_W0QQcmdZViewItemQQitemZ140563931332



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Jean Prudhomme