thump

Hello guys thanks in advance for any advice you give. I have an 05 vz exec and for quite some time it's has been clunking and thumping and thudding over bumps at a decent speed say 80km +. They can range from quiet to very loud and can be quite scary at times. To me the sound is never...

whenever i am driving, i get a thump when i try to accelerate until it clicks down into 3. it mostly happens when i am on the freeway going from 80 --> 100, it will thump, thump, thump then click down, hestitate then away it goes. ive taken it to the mechanic, and they couldn't find anything...

Just put in a new alternator thinking it would fix the problem but she still goes flat every couple of times I kick her over. Battery isn't that old either so not real sure what the problem is. Also, I rekn I've lost a heap of power and everytime I change gears I get a big thump from the back...