I bought a set of aftermarket springs for my 69 coupe and when installing GM shackles I found the springs to be a bit less wide than the original spring. I am replacing a mono and it is approx 2 3/4 wide and the replacement multi leaf is approx 2 1/2 wide. Is this common and will it be a problem?

The difference should not be a problem. Make sure all bushings are lubed well when you do the install.

I didn't have any issues with mine (JCW 4 leafs)

What is happeneing is the GM bushings are touching in the middle and there is approx 1/8 inch either side that has not touched the spring yet. I have not tightened then down yet but just wanted to be sure that the width difference is not going to be a problem. In reference to the lube thing, what is the best to use on these.

You need to get multi-leaf spring bushings b/c mono-leaf spring bushings are wider!

I told good old JCW to send poly bushings that matched their 3-leaf mono replacement springs and got just what I needed.

That said, the poly pads probably will need have their lips trimmed if you are going w/ 3-leaf mono replacements, mine did! Mono's are 2.75" wide and thin on each end to 2.25" wide and thick in the middle!! Multi's are 2.5" wide all along!!

I used a boxknife VERY CAREFULLY to trim my poly pads!!

pdq67