Have an 07 Bravo 1 on an 07 Stingray. Was original from factory on boat. I am second owner of this boat as of 60ish hours. To my knowledge the gimbal bearing hasnt been changed and was checked while we had drive off over early spring. Had new built motor for it. Makes about 300 more hp than the original 350mag mpi. I ran it today for the second time since putting new motor back in. Notice while idling after driving on to trailer (had it in gear and hatch up while hooking safety chain) that i could hear a rattling sound coming from back of motor? Didn't investigate too mich before ****ting it down. Also drive was all the way up at this time like it would be for transport. It has never done this before until today. Nee motor idles around 980-1050rpm. B1 is the newer swept back style. Could this be a bad gimbal bearing or u joints? Didnt sound like cale train noise. Had a much heavier sound to it. I am absolutely stumped and help would be appreciated. Also the trim indicator simce we put drive back on is fine at low speed until i get into it pretty hard and then starts to act crazy and jump all over the place? Used alignment tool and got it very much aligned. Original gimbal besring as far as i know.

NEVER run the engine on a bravo (or alpha) equipped boat with the drive in the full trailer position- the u-joints will def. rattle. Drop the drive all the way down (or at least to the full trim position), and I bet your noise will be gone.

Could i have messed something up by doing that? We are talking about 10sec max. When i head it i shut it down.

Probably didn't hurt it, but if you want know and sleep good at night, you can pull the drive off and look at the input shaft. If you see any shiny spots where the yoke or center socket has been making contact, then you know it was up too high for sure. Make sure the joints move freely and it should be good. There is more room to prevent contact on the newer input shafts, I doubt you hurt it. But it doesn't hurt to check it.
Hope that helps.
Dick