There was a 1/2" lowering block that I removed b/c of the exhaust scraping the speed bump in front of my house. After I removed & tightened the U bolts up There is a loud thunk that sounds like it's comming from the driver side. Is there something I am suppose to install on there when there is no lowering block? The PO installed them, so I'm not familiar with them. If it makes any difference I have multi leafs.
Any suggestions?

When you removed lowering blocks, did you realign the center spring eye bolt into the rear end perches? Could you have tightened up the springs with the eye bolt out of the pocket and now all is loose? Could spring still be loose? Is the shock topping out? You are sitting higher now , right?.

When you removed lowering blocks, did you realign the center spring eye bolt into the rear end perches? Could you have tightened up the springs with the eye bolt out of the pocket and now all is loose? Could spring still be loose? Is the shock topping out? You are sitting higher now , right?.

I did forget to align the eye bolt. I 'll have to loosen it & check. It is higher, but not by much. Just a visual when I pulled off the side of the road to check, the leaf didn't seem very snug against the bracket that the u bolts thread through.
The noise is like a loud knock. I'm not driving very fast, maybe 20-25 & I can hear & feel it driving on smooth road.

There is suppose to be a rubber pad on the top and bottom of the spring. Are they in place?

There is suppose to be a rubber pad on the top and bottom of the spring. Are they in place?

No rubber pad at all. It looks like there is still a gap between the leafs & the upper bracket.

Just got underneath & noticed there is at least a .5" gap between the top of the leafs & the bottom of the perch. Could the perch be the wrong one for the mulit leaf thats installed? May have to put the lowering block back in. It almost seems like the perches were madae for a 5 leaf & not the 3 leaf I have

If you have the Hochkis 3 leaf springs then they were designed to fit in the mono leaf perches. They require a spacer to work in the multi leaf perches.

No rubber pad at all. It looks like there is still a gap between the leafs & the upper bracket.

Just got underneath & noticed there is at least a .5" gap between the top of the leafs & the bottom of the perch. Could the perch be the wrong one for the mulit leaf thats installed? May have to put the lowering block back in. It almost seems like the perches were madae for a 5 leaf & not the 3 leaf I have

Sounds like you found your problem.