I'm running a 3/4" rear spacer with Z71 springs and the N8030 Skyjackers.
When I started my axle swap I found out that If I disconnect my swaybar and leave my shocks connected I can set the frame on jack stands and let the axle down far enough that my springs would get loose enough that they might fall out.
You might try doing a few tests with your jack to see if you springs get loose. Try jacking up one as far as you can, that should reduce the weight on the other side, you might also try setting the frame on jackstands and then lowering the axle as far as it will go. Keep an eye on your eBrake cable and brake lines when doing tests like this as they could server as limiting straps
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If I were a betting man, I would still say something with the shocks aren't tight, possibly the top bolt?
I needed something like 14 washers per shock to fill in the gap.