Help diagnosing downshift noise
 

So I just rebuilt an 89 pickup 3.0 6 cyl. It was a gift from my buddy- we rebuilt the engine from the crankshaft out. New everything, including clutch. This is my hunting rig, so I need to know it's not going to leave me stranded somewhere above 10,000 feet in the mountains. Here's the issue on my mind; the clutch has been replaced with a total kit including TO bearing, pilot bearing, pressure plate, etc... When I'm driving down the road and downshift, there is a brief "growl"/vibration that FEELS like it's coming from somewhere between the flywheel and the carrier bearing. The carrier bearing does have some play in it; I checked. However, there is no noise when just coming off the gas pedal, nor is there any kind of noise during acceleration. The only time it makes the noise is during downshift when the drivetrain has to come up to match the rpms of the motor. I've read other threads regarding similar concerns and they've left me rather confused. The TO bearing is brand new and the carrier bearing should be making noises at other times than JUST downshift/clutch release. Any ideas? Help me out, fellas!

What gear are you downshifting into? How fast are you going? Sounds like slightly worn synchronizers in the transmission or completely normal depending on how loud the "growl" is.

I think I've figured out what was going on... it turns out the sound was due to my timing being off... bad! My distributor shaft was off one tooth, and was as far as it would go to one side to get it to 10 deg at idle. My engine was also gutless as hell, and upon removing the shaft and turning it back one notch, the power jumped right up where it should be and the sound was gone. I surmise that the sound was due to back pressure in the intake or premature exhaust pressure. It was making the sound in ANY gear that I downshifted to while leaving off the gas- like anticipating a turn, shifting down through the gears with the foot off the gas, until getting into 2nd gear to make a slow, sharp turn into a parking lot or driveway. But since I got the timing on track, the strange growl is gone. Thank you for your thoughts, nonetheless!