I have an 89 xj np242 with re1801 sye. I used a front drivesahft with a spicer flange for my rear driveline. Well I busted a u-joint on my last outing and replaced it today. Now i have horrible driveline vibes at all rpm. Ive checked all the joints and everything moves great(no binding). The one thing I do remember is when replacing the joint some of the needle bearings on the cv joint fell out when putting the assembly back together. So this is probably a stupid question but will that cause horrible vibes?