OK I just posted that I thought my front flange nut had come lose again...I put her in neutral, crawled under and much to my surprise there is no play up and down with that flange. Car is on the ground but when you try to rotate the front shaft left to right there is just that slight movement but no play.

So I went to move it, I put it in reverse it goes right in gear as I am backing up after about 5 feet I feel this like thud. Like when the transmission goes into gear a little hard. But the car was ALREADY in gear and moving...when it engages in reverse there is NO noise and it immediately goes into gear and lifting the break she goes back. But only after going back a few feet does the thunk happen...it did it 3 out of 5 times that I tried it. Does not happen in drive
But I am getting that vibration so I am at a total loss? any ideas

 

you cant test for slack with tires on the ground. everything is under tension, even in neutral. must lift at least one wheel, preferably both.

report back after investigating both driveshafts with this method. look for play in pinion flages as well as output flanges, and look for play in u-joints.

 

it is just very strange the tranny goes into reverse perfect foot off brake immediately goes back but after a few feet it is like a delayed thunk I am wondering if it is the roto flex joint? the power goes from the tranny to the TC then to the wheels I can feel the thunk comingfrom seems under my seat and the delay is what gets me the car is moving if I leave it in gear with my foot on the brake Nothing
not until I start to move then it happens

 

Tension is a weird thing. I have to second KingKoopa's advice. get the weight off those tires and re-check. You may have completely different results.

 

What could rhat be. I went under to check my frint drive shaft and lifted the 2 front tires. When i rotate /spin the wheels, theres a big delay before the drive shaft turns. Is that normal? If not, what shoud I check or replace or tighten. Thanks

 

That's normal. But there should be very little delay before the wheels turn when you rotate the driveshaft.

 

Turns out it was the front U joint both sides went bad...and went bad FAST
I had literally just been under there and checked them not even a month ago

Replaced it with a HEAVY DUTY balanced shaft Im going to go ahead and do the rotoflex on Monday and then EVERYTHING is done