1986 GMC Jimmy vibration

After starting my truck, and putting it into drive, there is














































































































































































































































































































































































































































































when I put my truck into gear and start moving. An overall vibration starts that pretty much vibrates the whole truck. It doesn't feel like a front end out-of-alignment vibration. And it continues when I put it in neutral, and continue moving. Its almost like when you go over a road that has grooves cut into it. Don't know if that makes sense