Definitely not TC, most likely in the tailshaft but i'm baulking at a nearly 1k price tag to replace it so i'll look at everything else first.

 

Drove 200 plus miles yesterday..as long as it's under 70 mph feels normal.
But would like to fix it if something's wrong will take in and tell him what has been pointed out here and up date.

 

Follow up..as mechanic drove it originally with my wife and said it was the Torque Converter, and that anti shutter fluid usually solves it. He put the fluid in and we still felt shutter.So I figured if you gotta change Torque Converter might as well do the whole thing and rebuild transmission..what do I know I'm a guitar player not a mechanic.We pushed him to let's get this done.Instead he calls my wife on a Sunday and says the transmission rebuild guy is here Id like to take car and drive it.They get in car and drive around for 45 minutes. They come back and say not torque converter it's the Drive Shaft.
On the advise here I quickly ordered the GKN
(hopefully) drive shaft one from Parts Geek which came UPS Ground in two days with like no wrapping on it and mechanic put it in the next day. Car feels tighter and responding better but haven't gone on a road where we can go over 70 yet to test it for shutter.
He said the drive shaft was very worn.
Will update if problem cured.
Now a new problem need replacement key : (
Many thanks for advise.

 

Over 70 no shudder any more..drive shaft as was said her was the issue.Then our fob key failed and getting two of those cost much more than driveshaft job. Now I hear a bit of a thump when are braking but mid way decide to keep going instead.
Now gotta check into that.

 

Had a similar issue and just had the drive shaft replaced and it solved it. $300 for driveshaft and $160 in labor.

 

This was $398 for the OEM GKN from Parts Geek who sent it UPS from near by Pa but with no box and almost no wrapping around it..not sure I would order from there again.
And $200 labor.