I have this 72 3.5, (US named 450SLC) and I am running rich, some books read for a adjustment to lean down under the dash on the passanger side against the firewall. The only device I found that may look like that is a alumium finned unit that has a turn dial on the bottom to the left of the unit in which you can turn clockwise or counter clockwise. Is this the unit for adjustment? If anyone knows please let me know. Thank You.