This steel adapter has a male 18x1.5mm inverted flare (concave seat) fitting on one end and an 8AN male (3/4-16, 37° convex) on the other. Sold individually.
This adapter will also fit the inlet side of the Bosch "044" (FP200) fuel pump or the newer Bosch FP200-7 Fuel Pump when used with a Crush Washer (Part No. 3278-M18, sold separately).
Convex vs Concave