The GMS 61 & 76 & Tower 61 & 75
Weight: 19.4oz (550g) without muffler

Center distance width across mounting holes: 2.0" (52mm) Center distance length of mounting holes on same side: 1" (25mm) Length from front of crankcase to backplate screws: 4.0" (103mm) Width across mounting flanges: 2.4" (61mm) Total height of engine: 3.8" (101mm) Length from center of head to front of crankcase: 2.9" (73.5mm) Widest width of crankcase neglecting mounting flanges: 1.7" (43mm) Length from front of crankcase to center distance of front mounting hole: 2.4" (61mm) Height from crankshaft center to top of head: 3.1" (79.5mm) Crankshaft thread size: 5/16-24

The ST 61 & 75

Weight w/o muffler: 588g (20.63oz)
Weight with muffler: 766g (27oz)
Width between centers of mounting holes: 50mm (1.97")
Length between centers of mounting holes: 20mm (.79")
Width of crankcase excluding mounting flanges: 42mm (1.65")
Length from backplate to front of drive washer: 97mm (3.82")
Height from bottom of crankcase to top of head: 105mm (4.13")
Crankshaft size: 5/16-24