#1 #1 What I would do is get the wheels up on blocks on all 4 corners so you have room to work & add cardboard/tile etc under each block till you get it level side to side and end to end. Then as said if the trans is down 2 then you want the pinion up 2 (& vice versa) then move the pinion down an addit'l amount to account for pinion climb (iirc you said cruising/no hot rodding so not much might be needed) so add in the addit'l down amount the guys here recommend. You can raise the trans with washers above the mount or lower it by slotting the 4 bolt holes in the crossmember as needed within reason so that you might not have to use the rear axle shims or even rewelding new perches but find/post your angles. The only other caveat is you dont want the shaft angle on the front end of it to be the same angle as the trans and on the back end of the shaft you dont want the shaft to be the same angle as the pinion (need 1-2 deg difference on each end of the shaft). in other words you dont want the shaft and trans in a straight line and the you dont want the shaft and the pinion in a straight line. Keep in mind you are wanting to check the relationship between the angle of the trans and the angle of the front of the driveshaft (which is the front ujoint angle) and the relationship between the angle of the pinion and the angle of the rear of the driveshaft (which is the rear ujoint angle) cuz it is the ujoint angles that we want correct. We're only measuring degrees away from horizontle to get a baseline to get our angle numbers from as the car could be climbing up a hill & the ujoint angles would be the same. I hope that helps rather than making things more confusing. EDIT For the vibration check the amount of yoke engagement into the trans (want ~3/4-7/8"). My driveshaft was slightly too short & it caused a part time vibration in my 904/65 dart that came and went. The correct shaft quieted it. Also your shaft may not be balanced good enough, iirc yours is new but mistakes do happen