I am in the process of putting my swap together, (LS). I have been piecing the whole thing together and it is almost complete and ready to drop in. I have been bolting stuff together the past few days. Got the transmission and engine together yesterday, and then today i started mounting the accessories, once i finished i was messing around and started spinning the intermediate shaft, and noticed it is making a strange noise, not sure how to describe it, when spinning both axles things spin, and also if you spin the Input shaft on the tranny the axles will spin. Through my investigation tonight trying to figure out what might be the culprit, i have noticed if pressure is put on either of the axle 'Holes' then it is quiet, like, if the int. shaft is bolted up yet and is kinda "hanging"there it'll sound betterm and if i put the intermediate shaft in the passenger side to spin it, it sounds okay.. I have tried looking for a breakdown of the trans to see if there might be a bearing or somthing there that could have gone bad. Does anyone have any ideas? I am assuming this is not normal?

 

Those are the differential hypoid gears. It's a used transmission so they can be loud at times. If you're really concerned about it, have it rebuilt - either by yourself or a respected transmission tech.

 

I just didnt want to put it in to find out its blown.