If this is belt noise, it is apparently common. The engine stops too quick for the belt and there is a quick screech. Mine does it on occassion, mostly when she's good and warm. I've read the same comment here on the site a couple times. A weakening 'tensioner' can contribute to this too.
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93. 5 D250 4X4,HD Spring Pkg, Rancho 7000's, Rear Swaybar,Dual Shock Front Stabilizer,BD Injectors,31/2" Mandrel bent exhaust,16cm 'Hot End',Modest Pump Tweaks/Timed,K&N Air,Isspro Pyro,Tach,transmission Temp,Auto Meter Oil Filled Boost Ga. , 3:54's, 4 Speed Auto, Clubcab, Aftermarket Reclining Buckets w/ctr Drop Down seat/console, Black over Silver, 21psi,285-65R-16's,American Racing Clear Coat Mags, Amsoil 15W-40HD Marine,12,000 lb. Warn Winch,KC Spots. 97,000 Kms.