Gas guage outer ring not seating

[LAV]

I’m installing repro gas gauge. I can’t get the outer ring to seat with the gauge assembly in place. I remove the gauge assembly and I can easily screw the outer ring in place, nice and tight. I have followed the schematic for the gaskets and I’m confident this is done correctly. I have done this before on another car and didn’t have too much of a problem. Thinking gauge assembly is unit is way out of specs. Any suggestions?