Can't figure this out. Thumping noise from the back

[hondanissan]

So I have an S14 and theres a sound that is coming from the back of my car. Its a thumping sound...like a midget knocking from under the back of the car. And I know there isn't a damn midget back there or in my trunk. I don't think its my vlsd or wheels or suspension.
However, this is the only way I can describe it. It used to thump lightly at low speed, usually in the beginning of 1st gear as I accelerate it gets louder and faster corresponding to the speed then it continues onto 2nd gear and finally goes away in 3rd. Now this was before I installed rucas. Now that I installed rucas, it's louder and more consistent all the way to 4th gear. As I accelerate, the thumping gets faster and louder. I don't have a clue to what this can be. I'm thinking it is coming from the drive shaft? Maybe my axles?...but they are still in great shape, I just inspected it today.
Help me out here. If you have ever experienced something like this or close...I need help. Thanks guys.

[Deftec]

Check your driveshaft bolts...they may be loose.

[swiftdrift]

Could be your sub-frame bushings!

I had a similar problem where it made that noise when i turned right at high speeds. Check those out.

Might wanna invest in some collars or replace the bushings....

[WangonwWarrior]

broken axle maybe or even a bearing

[hondanissan]

first thing tomarro, after fishing, i will check those out guys. I dont think its my axles cuz they still look clean and feel solid. but i will never the less check them all out. thanks.

[jackjack]

midget???? ahahahhahahaha. same here. check the bushings.

[emersonLP]

Check your subframe bushings and diff mounts. Make sure diff is snug.

[shmiddy]

its def the axel my 300zx had the same problem. i herd a thumping noise everytime i pull off from a red light. a deep pitch sound right

[aznpoopy]

+1 axle

had this problem before

[hondanissan]

alright guys. thanks for all the input. they are greatly appreciated. it definitely sounds like a thumping noise when i accelerate...kind of like someone tapping hard on an empty barrel. I'm doing a rundown on all those parts...as soon as get a lil rest from the fishing trip.