Yes, mine is Infinity OEM sound system.

I am sure this can be helpful if you don't mind spending $50.
Scosche FM-MOD02 Play your iPod®, satellite radio, or portable music player through any car's FM radio at Crutchfield.com

I wish I would of seen this option before I had installed a aftermarket radio in my 99 montero sport.

FM modulators only work good if you live in the country and don't have the airways full of different stations. Once you get near any big city there is so much interference that it becomes a challenge to find an empty spot on the spectrum. I have used couple different modulators and I must say they are more dangerous than texting while driving. Here is why: you have to fiddle with the radio to find a relatively empty frequency spot, note the exact frequency, tune your transmitter to the same frequency, only then you can play your music or podcast. Guess what 15-20 minutes later you have to pause and repeat the process because some extra noise and static starts to come in on that channel. You discover that you just picked up a new station that is now interfering with your transmitter. You end up fiddling with all controls until you give up and start listening just to the radio or CD.
Modulators work in the bind but not really a best option. I am very happy with Grom. Unfortunately they do not provide any support for aftermarket stereos. That totally blows because I wanted to do the same on my other vehicle which came with the aftermarket player.

Which Grom Kit?
 

I have a 2004 misubishi montero limited and I’ve been trying to figure out how I can play music from my phone. The after market stuff just gives a bad sound quality from what I’ve Hurd and I stumbled across this comment. How’s the quality with the grom? And can you send me the link to the one that you bought.

I bought mine from this website:
https://gromaudio.com/
5 years later - still no issues.

Was it an easy installation?
 

Out of curiosity was it a easy install job (female and male connector connection) or should I expect to have to direct power into the grom from one of the wires that originally belonged to the cd player

The unit came with the connector that plugged directly into an existing plug on the back of OEM CD player. I had to locate an Ignition ON (+) to connect to and to route the AUX wire out to wherein wanted it to be. That's it.