Front End Wobble

Hey All, I have a '93 G20 conversion with the 350. The van has almost 200,000 miles and I don't believe has ever had anything done with the front end except maybe alligned prior to my buying it about a year ago. Before taking about a 2,000 mile trip to Texas and back last week I replaced the front wheel bearings. Everything went fine and the van drove great right up until we stopped to exit about 5 miles from home. Upon slowing down from 75mph to exit we noticed a "wobble" in the front end. When going between 10-20mph the front end feels like its wobbling this movement does not transfer through to the steering wheel which stays straight. At higher speeds the "wobble" smooths out and only a vibration remains. Yesterday I raised the front end and did the "push-pull" check on the top and bottom of both front wheels to check the wheel bearings, they feel solid. When I "push-pulled" on the sides of the wheels the driver's side wheel seemed to move more than I would have expected and it appeared that the control rods were moving. I have never worked with front ends much and am not sure how to diagnose this problem. Any help would be appreciated. Thank you.