So (and I am sure this has been discussed before, but I couldn't find anything on the SEARCH results) my OEM alternator finally went out and when I went to replace it - EVERYONE has a 5 groove pulley on theirs and the original is 7 grooves. The original serpentine belt is 7 grooves. Why is there such an issue with the new alternators being manufactured out there and what has anyone else done as I know I am not the only one? I swapped my old one in for a core exchange and when I took the new one back (almost a week later) they shipped out the old one.
Thanks!

 

That is a real bummer! I looked around on the web, for what it's worth, even in the Mitsubishi parts program the pulley is shown as a 5 rib. Any chance your engine was swapped at some point?

I had to look up the 2004 Montero with 3.8 liter to find the 7 rib pulley, part number MD619827

The 5 rib pulley is part number MD618817

I've stuck to OEM alternators from the junkyard or the dealer, or, when that's not an option Denso alternators have held up beautifully... They seem to be a little harder to come by these days. Everything else from the discount autoparts store seems to die out on me too quick.

I would go back to the store and return the alternator if they can't locate the correct one. Try going up a few years, I think the 7 rib belt was for the full serpentine set-up. If that doesn't work, you could try Car-Part.com--Used Auto Parts Market to browse nearby junkyards, or, hit up the dealer and ask them for the MD619827 pulley. I checked around online and couldn't find anyone with it in stock, even my south american and japan resources show it being out of stock. Good luck on your quest!

 

You have to keep in mind that for some replacement alternators you have to swap the pulley from your old one to the replacement. Too bad you did not notice the difference before returning the core back to the store. I'm sure you should be able to find a replacement alternator pulley.