You will need a 14 mm
The 2001 Chevrolet Silverado-2500HD has a 6.0 L base engine size.
The 2001 Chevrolet Silverado-1500 has a 4.3 L base engine size.
The 2001 Chevrolet Silverado-2500HD has a V8 engine.
The 2001 Chevrolet Silverado-1500 has a V6 engine.
18mm
3/4" or 19mm
35 mm
36mm
try a gator grip socket or pound on a smaller size
35mm
34mm or 36mm
36mm should fit