I've noticed in my truck and when I had my 5 speed Mustang GT years ago, that when you let off the throttle somewhat suddenly, without pressing the clutch at all, the whole vehicle seems to jolt quickly. Say for example, I pull out and shift normally to 4th gear, then a car cuts me off, and I immediately release the throttle without clutching at all. The whole truck jolts. Doesn't make any clunks or bad sounds. But I was just curious as to what this is and if it does any harm. It gets progressively worse the higher the speed of the truck and RPM's. Usually doesn't do it at lower speeds unless RPM is high. My truck has a fairly new Southbend clutch and the Mustang I referred to had like 30k on it. So it seems unlikely anything is wrong with the vehicle, I was just always curious what exactly was going on and if I should take extra care to avoid it whenever possible.

I would have to say it is the torque of the engine. I had a 68 Chevelle SS 396 in my younger days. The big block had a lot of torque. Mind did what you were describing.

Kind of got the the same thing its like a bit of slop in the gears or drivetrain. I normally it doesn't bother me...

Might also look at all the bushings in the suspension, and motor mounts. Check the rear springs, u-bolts and axle for breaks or cracks just for the heck of it. Mostly just to rule it out.

I'll take at a look at all that stuff when I get a chance, but I'm not very concerned about something being wrong with it. Especially since the Mustang I had was in excellent shape an also did it. It just seems to happen whenever RPMs are a little high for whatever MPH you are moving, then release the throttle suddenly. Never happens when I'm just normally driving unless something unexpected happens or I just get sloppy for a moment.