Recently I asked for ideas on how to stop a 2.5 inch shaft from rotating after engine failure and while operating on one engine. This has been a very interesting exploration. I received lots of good input and the suggestions were mostly practical. One comment was to definitely tie the shaft down while another suggested it might not actually be necessary. This led me to discuss this matter with ZF which I probably should have done at first. I was put in touch with a knowledgeable and helpful engineer and their recommendation for trailing (aka freewheeling) situations is to tie down the shaft if possible. But if that is not possible they recommend filing the gear housing to the top with oil, allowing the shaft rotation and monitoring the temperature to keep it below 176 deg. F. They expect that this should allow about 8 hours of trailing. In most cases that should be enough time to get to a port. The excess oil must be drained prior to engine start. Their operating manual indicates that adding the extra oil is not needed if the trailing operation is limited to 6 to 12 hours, but the temperature must be kept below 176 deg. In any case. My interest is in emergency engine failure situations but the manual addresses situations where boaters experience trailing while intentionally operating on one engine. Again, the key is to keep transmission oil temperature below 176 deg. Thanks to all who responded with ideas! Joe