Vibrating Van HELP! 88 2wd

I had a small clunk when decelerating as I almost stopped and it has developed into a serious vibration (Or I have a new problem). When i accerate to 60-65 mph I get a terrible shaking that continues to shake untill I am almost stopped. when I get down to 10-15 mph it smothes out and doesn't come back untill I get to 60-65 again. I feels like it's from the driveshaft area , but that checks out ok. I shakes so bad the dash bounces. I've checked out the whole front end, u-joints, brakes mounts..... It drives like it's new up to that speed then starts in again. I'm puzzled by it continuing to shake untill I'm almost stopped and then smothing out. the u-joints are non greasers. Could one be dried out? I'm thinking torque converter, but I don't know. Any help would be awesome. Thanks in advance.

If you can induce the vibration at 60 MPH again, then place the transmission in neutral, allow the engine to idle, and coast to a slower speed, does the vibration still occur? If the problem were due to a torque converter, this should help identify it, since the torque converter turns at engine speed, not road speed. With the transmision in neutral, even the turbine in the torque converter would not turn any faster than the engine.

Another possibility is front end alignment. Significant toe or caster problems can induce "porpoising" in the front end (especially a loose front end) and will not stop until road speed is reduced or the brakes are applied aggressively.

Ding Ding Ding.... we have a winner.... Well, kind of. As far as I know so far... It was the front end. I think my idlers just got bad enough to throw it into a shake and rattle untill I slowed her down. My factory ujoints are still smoth as a babies butt. I did the one turn fix to the idlers till mine get here and the vibration is gone. Thanks Bow tie guy... I never even thought about the front end doing that. After my 63 falcon that you could turn the steering wheel 4 inches each way before it started turning, I never would have guessed bad idlers could have done this. Ok... Thanks again. If you ever need any help with a VW beetle... let me know...lol

Anyone with a Beetle needs help. ;)

I had a '63 and '68 Type I, and a '68 Type II (Transporter), and for a very short time had a '68 Karmann. They were not bad vehicles, but I think I'm about done with them. I've had my fun. All of them needed clutches (easy job - No lift). All of them needed heater boxes (not such an easy job when everything is rusted despite the oil-leaking push rod tubes). And all of them needed constant carburetor and valve adjustment. I had actually restored the '68 Type I to a very nice condition and drove it until I got rear-ended at a railroad crossing waiting for a train. After that, I knew I didn't want to be in any higher speed collisions with anything like that.