My Mystic Teal Z28, "Thrummer", thanks for the help

This is my 95 Z28,...I ordered it,carefully, new from the factory and drove it mostly in stock trim for it's first four years. 90% of the first 100K miles of "road seasoning" happening on a beautiful,wide open stretch of winding smooth highway running through the mountains of Vancouver Island for 300 miles round trip each week.
I did the trip for many years and knew the highway well, there where long stretches where I could dial up the speed, sometimes even on cruise for quite some time.
I really don't know if there are many Z28's that have as many clicks at 140Kph plus.
The car was super stable at speed and after driving an RX7 on the same route for years I used to joke that I could read a book at 140kph+ in the Z'd(In the RX7 anything over 110kph and things started shaking and you had to pay attention).
At 140kph the Z28 had just one thing that felt different than at any other speed, it "thrummed", a steady, low level,slow oscillating thrumming sound that I chalked up to the driveshaft at high rpm in 6th gear. It was'nt obvious to anyone but me.

At the end of 4 perfect years a sibling bought out the lease.
It got wrecked once, painted the wrong color on rebuild, had a built 383 installed and blown up and was generally abused.
It sat in my folks driveway for 7 years without a motor/trans.

I got it back 6 months or so ago and using this site tore it down and built it back up again. I could not have done it with out the help of many here.
Thanks.

It has a lot of mods and is configured for the kind of driving I like, mountain highway cruising and some sensible canyon carving.
I built another 383 reusing what I could from the first 383,...I went with the Lunati VooDoo 211/219 cam and love it.
I'm running the Fidanza light flywheel and at 112LSA and 800rpm idle it lopes but runs smooth and strong from 1,200-5,500 rpm.
I appreciate the suspension mods most of all,...Prolines/KYB shocks/struts and BRM swaybars, SFC's,Strut bar, LCA's/PHB. It's way tighter.
It came back to me with 3.73's and I had my HD driveline fren rebuild the T56 and added a hurst shifter,...I'm running a Stage II clutch.

While I was building this car and looking for parts I stumbled across a MINT dark green 94 M6 Z28 with black leather interior for way,way less than $4K and my grrlfren now owns that. It's stock other than a CAI and I'll tell you, IMO, at least in the city, IT's a way nicer ride,...but mine is an unreal beast on the open road.http://images.ibsrv.net/ibsrv/res/sr...ech/gr_nod.gif

I'd like to thank everyone here who's helped me with info and parts, people like PHStratton, lees02WS6, justjachimiec, Tireburnin, STS95T/A, zman1969, za355tx, MJs1FastSS, dphc18, 95zBuild, VIPRETR2, bigbusa1, daniel044, 1BadAzzWS6, rollercam, JasonShort, ROCNDAV, and ESPECIALLY
ShBox.