Mercedes-Benz 2009 GL320 BlueTEC Operator's Manual page 426

Technical data
Engine
Model
GL 320 BlueTEC (164.825)
Firing order 1-4-2-5-3-6
Poly-V-belt 2 035 mm
424
21 21
GL 450 (164.871)
1-5-4-2-6-3-7-8
2 404 mm
21
GL 550 (164.886)
1-5-4-2-6-3-7-8
2 404 mm