So, after getting dumps put on my car, I figured it might be an issue with those, but the vibration doesn't occur all the time. Under load it isn't there, and it seems to be speed related (u-joints???). I havn't noticed it at any speed under 40 or so, but when I'm cruising in 4th/5th gear, and I put it in neutral to coast to a stoplight or something, it vibrates. It doesn't feel severe or anything in the seat at all, but the steering wheel shakes a bit. Would this be an issue with u-joints, or maybe just bushings wearing out? The car is a 1995 Mustang GTS, mods in signature - stock suspension.