I just got done with swapping out my 12 bolt for a 14 changed ujoints to the correct conversion u joint. im getting vibrations going like 10 miles an hour havent gone faster than that cause i dont have brakes. my lift block that i had were really big but it amounted to a 4 in lift im guessing the springs werent arched and it was just the blocks giving it the lift. the blocks im using now are significantly smaller cause my ubolts wouldnt fit i got the blocks off of a trucks that had a rancho 4 in kit. is it possible that the driveshaft has to be lengthend? im going out to get the ubolts for my old blocks probably tommorow the other thing that concerned me was that i had a hard time lining up the holes where the perches and the leaf springs met off by an inch to 2 inches had to pry on the leafs to bend them to line up. it fit well on my old truck with no problems so I dont understand where all this trouble is coming from. the last thing is do the which way do the blocks slant i have them where the slant going up is facing towards the front of the truck. any imformation regarding this can be very helpful to me.