Death Wobble from 40ish-50ish mph when o/d is on... help

[96ramJimmy]

So I've been having an issue with the truck, 1996 Ram 1500, 2 door 4x4 5.9L 360 I believe its a 46RE transmission. So the issue is when I'm driving and the truck hits OD the whole truck gets a real bad shake between 40-50mph(only between those speeds). If I turn OD off on the button there is no shake at any speed. At first I thought is was my tires we chopped up but now I wonder if its when my converter locks. Anybody have/had the same experience? Any ideas what it could be or what it is? And any tests that I could do to help narrow down what it could be without shelling out a bunch of money.
Thank You.

 

[Joe w.]

Mine does this sometimes at the same speeds. I've been told it could be the overdrive gear in transmission but not sure if that is it. I've always thought it was probably u joints on drive shaft but they are ok

 

[Daw14]

Is the engine rpms dropping to low causing it to bog down . If you wait to shift to od until a higher speed ,say 62 does it display the same symptoms? Could it use plugs,or complete tune up? Check motor mounts and transmission mount.