Product review (5 stars): Whirlpool 8181670 belt: Does cross reference w/ W10388414
Purchased Whirlpool belt 8181670 through Amazon but received belt W10388414. Thought I had been shipped the wrong belt, especially after comparing with my 10 year old belt* (see bottom of post).

Contacted seller, Appliance Care Store, while still thinking that they had shipped the wrong belt. They promptly replied less than 24 hours later stating that the part shipped was a direct replacement for the part I thought I'd ordered, but due to my description of the belts not matching offered a full refund upon receipt of the shipped item and included a Return Authorization. So after reading and double checking online, it is the correct part. When comparing the new belt with the old belt, the new belt was wider and a little shorter than my old belt, which is why I really thought they had shipped the wrong belt. Apparently the old belt had stretched about an inch. The new W10388414 belt did go on very tightly, you just have to loop around motor spindle, then hold belt onto one side of pulley and slowly turn pulley around bringing the belt onto the pulley - like putting a chain on a bike. It makes sense that the belt should be really tight since it only uses friction to transfer from the motor spindle to the pulley.

*The belt had already slipped off once due to a loose nut allowing the wash drum pulley to wobble loosely.. which then wore out the belt on one side. All this time I thought I needed new shocks for my Whirlpool Duet because the washer would make a pretty good racket when spinning on medium and high speeds. Shocks not being cheap to replace, was waiting until they failed more. So needless to say check your large nut that holds the pulley onto the washer drum, it may be loose! Easily accessible from the back panel.