My guess would be wheel balance.
because that's kind of a big engine
There are several things that can cause your 1995 Chevrolet Blazer to shake when accelerating. Bad spark plugs and spark plug wires can cause the vehicle to shake. Tuning up the engine may eliminate the problem.
Engine miss or rough idle, or broken motor mount
Need more info. Does just the engine run rough or does the steering shake or does the whole vehicle shake betwen 50 and 55 mph?
it might be a broken motor mount. there are two mounts located towards the bottom of the left and right side of the engine make sure you are getting spark to all cylinders. (check for Misfiring)
It's almost always warped rotors.
YES it can, but the engine would vibrate and shake if it did.
The symptoms of a 4.3 liter V-6 engine timing chain problem is an engine that runs very rough. The engine will shake violently.
bad tires, wheel alignment , bad tierod ends, start with tires may just need balanced...its the cheapest
if this happens at a certain speed it's probably the alignment of the tires.
either the idle is set too high or your timing is advanced too far.