I was busy mowing along yesterday with the 60" deck on my JD 400 and hit a limb segment in tall grass I didn't see. Normally that deck will simply pulverize whatever gets to the blades, or fling it out the discharge. The limb segment I hit was just too big for it. It stopped the blades for an instant, then the belt jumped the pulleys. I want to go back on with a new belt today, but the JD dealer isn't open. Once something happens with a belt, I replace it. My theory about why this one jumped the pulleys instead of stalling is that the inside track is getting worn, therefore it's getting loose, which enabled it to jump off when a less worn one wouldn't have. My JD p/n is M48444. Here are the JD specs for the belt: M48444 price: $31.99 Belt Section HB Effective Length 144.3 IN Width 0.66 IN Thickness 0.41 IN Angle 32 Gates says their B140 is the equivalent/substitute belt (144.0" vice 144.3"; however, I can take care of a small difference like that with the tensioner). I can get the Gates belt today or tomorrow, and be back in business mowing Monday. Gates cross the JD M48444 over to their B140 The JD price isn't bad, and I normally would use the dealer supplied belt. I can get the Gates for $18.96, through a discount. Gates is a reputable company, and if they say it's a match, is there any reason not to install the Gates belt?