Hi Andrew my name is Greg. I've been reading through your thread on the driveline vibration issue and I too have been chasing a vibration at highway speed. I have replaced every thing behind the engine and is still there. could you possibly share with me in lay-person terms what the angles should be. I just installed umi adjustable upper control arms and I want to try and adjust the pinion to see if it helps. here is my combination; 66 chevelle 408 cu.in sbc, solid mounted quick time bell housing tko 600 modified by Kiesler. custom drive shaft with 1350 u-joints. 12 bolt rear with 3:55 gears and 275/50-15 mt drag radials. I have broken many transmissions over time chasing this issue along with drive shafts and pinion bearings. as i'm sure you know i'm beginning to lose my sanity over this issue. thanks for any information you have to share.