JW - You are absolutely correct. I continued testing and driving and discovered I can totally stop the chatter by nudging the shifter slightly towards fifth gear and make the chatter louder by nudging slightly towards reverse. So I will just drop the engine/tranny again, pop off the front cover and re-adjust the fifth/reverse slider. No worries. Easy as pie.
And as for the 7:31 swap, I find that driving in fifth gear (to eliminate the chatter) produces a totally quiet ride. No whirring. No grinding. No humming. Nothing. Fast, slow, throttle, brake. It is totally smooth and better than ever.
And I should emphasize that the ring/pinion swap was accomplished using only a brief paragraph written by you in response to a question I posed about setting pinion depth. No other documentation was required.
So John Walker, for the record, you are a genius.
Thanks,