alternator belt problem on '90 Dakota

This NG has been helpful before (MUCH appreciated) so I thought I'd give a holler.
1990 Dakota, rear wheel drive, 2.5L 4cyl, five speed, w/AC died and
would not crank. Replaced battery and it fired up. But it died again when battery cable was removed. Put in new alternator. Fired up but, after just a few seconds, made a rattling noise. Shut it down and found alternator belt shredded. Replaced belt and bumped ignition, then checked belt position. It still wants to throw off the front of the center pulley where the smooth side of the belt is routed. Can't seem to solve by adjusting tension. Any ideas?
Of note: New alternator seems deeper (front to back) than old one. But parts stores were already closed yesterday when I got to the current point. Could it be the wrong part with the pulley too far forward?
Thanks in advance, folks.
Karl
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On 3/5/2012 7:31 AM, Ka-POP! wrote:

Never, ever remove a battery cable with the engine running--that will blow the alternator, and sometimes other things.

Sounds very much like the wrong alternator, and yes, that could/would screw up belt alignment.
--
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Careful there Peter, we don't don't want to here any "I got my penis caught in the fan belt while removing the battery cable" posts! Bud reads here you know.
beekeep
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On 3/6/2012 7:51 AM, beekeep wrote:

Good point!
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On 3/5/12 6:31 AM, Ka-POP! wrote:

Turns out it wasn't the alternator itself but the PULLEY on the alternator. New pulley had 5 blades and was easily 1/4" thicker than the old one which had only 3. The Auto Zone shop still had my core return so we swapped the pulleys and the old truck purrs like a kitten with no belt slippage.
Interestingly enough, this is the second time I've run into this. The last time was with a 1987 Toyota Tercel. They were made differently before and after May 31 of that model year so I thought that split might have been the difference. But no such mid-year difference appears to apply to the old Dodge. So I'm guessing all new alternators are made with thicker pulleys? Dunno what that's all about but I'm definitely filing this in the ol' gray matter for future reference.
Karl
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On 03/05/2012 07:23 PM, Ka-POP! wrote:

Thanks for the followup, we don't get those often enough. You should make a joke about Bud now.
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