I have read that these cars can twitch from touque applied due to the geometry of the four wheel independent suspension. My 88 Vette has a slightly modified 350 and 3.55 gears, it is not like the thing jumps lanes but it is unnerving. Due to the nature of "joy rides" at dealers, I can't just go drive another to see. Do/have any of you had the same experience? My car is a 71,000 miler and I can see no obvious wear issues in the bushings.

not completely sure what you mean by a twitch but my vette (actually both of them) handle great. the only jumping they do is when i punch the gas. maybe some of the modifications are causing your condition.

If you're feeling the rear of the car move side-side when you get on-off the throttle, check the rear wheels bearings for play. Another thing that can cause that is bushings in the trailing rods, as well as strut rods. Also, the ball joints in the toe arms/ links can cause this. I've seen more loose wheel bearings than anything.... Depending on how loose they are, you can remove the half-shaft, and tighten the nut up to remove the play. If the twitch goes away, and there are no new noises, you should be good to go, but you may wind up replacing the bearings in the future.
 The alignment can cause problems too, but not usually something you would notice when getting on/off the throttle like that. 

I am doing a full polyurethane rebuild sometime soon, when time isn't such a factor... The car drives totally straight, the twitch is only under extreme throttle changes. I will check the bearings, I was more suspect of a bushing or two being worn out.

Could be worn U Joints.  I have the same problem.  New U Joints are going in this weekend!  I'll let you know if it cures the twitch!

prothane bushing kit as Summit raceing is $145.00  compaired to the corvette specialty suppliers   NO one has a kit with every bushing I researched that most likely is wheel bearing or u joint  jack it up and go find it