1995 Chevy Silverado Vibration at 40-50mph

I have a 1995 Chevy 1500 extended cab short bed. I have 161k miles. I replaced the rear wheel bearing about a month ago and now I have a vibration at 40-50mph. It is rather noticable when driving(it will shake a soda can in the cup holder) when I am above 50 and below 40 all is well. I replaced the rear drive shaft u joint tonight and it helped some but it is still there. Any recommendations is chasing this down? Thanks for you help