The access doors have been relocated in this duct and the spool duct between boxes 3 & 4..
The elevation is to match the relocation on the side casing of the module boxes.
They were dropped on the module box due to the stiffener @ the lower header.
The doors are to be dropped by 2" in the CO/SCR duct & the spool duct between boxes 3 & 4.
In the direction of gas flow,
the doors just downstream of the inlet flange and the doors just upstream of the outlet flange are to be located at 2'-3 3/16" from center line of duct column to center line of door.