Product review (5 stars): Fit perfectly and works
My Maytag MDET336AYW has an appetite for these things; this is the third one it's had in 9 years.  This one fit perfectly on the existing tensioner arm; the axle on the arm wasn't damaged so no need to replace the whole assembly.
Don't forget to reinstall the thin nylon washers on either side of the wheel; they keep the bushing in the wheel from being eaten by the snap ring and the tensioner arm.  I wiped the axle with a paper towel to ensure it was reasonably clean, then used a little powdered graphite (the stuff in the squeeze tube you use on door locks) to lube it.