The spacer I made was 4 1/4", along with 2 flat washers between the bolt head and spacer, so spacer does not gall under the bolt head. I used this combination to remove my OEM coil spring off my 73 Comet, spacer length work out just right for me..........make sure you lube the threads, bottom hook body threads and between the washers! David
Four is likely fine. You could cut a couple two's and one's. With those you can have lengths from one up to six inch.
I know I have rented them (more than one) and the threads would be stripped off on one spot of the threaded shank. I was thinking someone used an impact on the nut...
I had to. It was getting to be an all day project turning the thing with a wrench, and then more limited the more it got tight or loose. My little compressor wasn't up to the task so I drove it over to a neighbor's like 3 minutes away half compressed.