Tyler went with a NEW T5z and still had the rattle actually. Ryan's 242 is silent with a JY box. My first one, various driveline setups, new output bushing, preload on the input and counter shaft, noisy as hell, quieted down a little with the V6 yoke. That one was a JY box that had a fresh rebuild, never even had fluid in it since the rebuild, but it leaked like a SOB even when properly assembled, so it's anyones guess. The one going in hopefully tonight, another JY unit, original Ford gears, billet countershaft retainer, preload on counter and input as well, and the Aerostar yoke (bigger weight than the other V6 yokes, not quite as big as the BIG yoke).
If you look at the earlier Fox's with the 4-cylinder/T5 combo, they had a huge balancer on them as well, but a smaller output shaft so that won't help us out. Kinda goes to the idea that it's T5/4-cylinder that just isn't a happy combo without some weight in there.