hard to tell without actually looking but like stated before check balljoints, hub bearings.
if the vibration goes away when your speed is increased then I would recommend a balance and rotate of your itres.
Def need to get looked at soon when it comes to balljoints lives are at stake.
'98 Dakota 4x2 3.9L, 5Spd-just bought
Clear corners, Cragar Blacked out Soft 8 rims with 245/75R16's, Hurst shifter,Flowmaster cat back system....
'71 Demon-too many mods to list!