Honda Pioneer 1000 2017 Owner's Manual page 270

The VIN and engine serial number may be required when ordering
replacement parts. You may record these numbers in the Quick
Reference section at the rear of this manual.
The VIN is stamped on the left side of the frame, located under the
rear cargo bed.
The engine number is stamped on the upper side of the rear
crankcase.
UNDER CARGO BED
LEFT SIDE
VIN
UNDER CARGO BED
CENTER
engine number