charger4@ptd.net
I used Retro sound 4x10 slim speaker. There are a couple of 4x10's, $100 one has stereo connection, can handle more power and is a bit slimmer than the one that costs about $60, it fit in with no interference to cables. Part number 410n I believe. Works great.
You simply got the wrong speaker sorry to say.
When it comes to other cars and applications you could add baffles or spacers maybe to fix this problem. But in that location there is not an option with out looking ridiculous .
Return the speaker and find a speaker that has the proper dimensions
Just an FYI for those that have run in to this problem. If you still have the original speaker, you can buy a recone kit from The Speaker Exchange. It isn't hard or expensive (I paid less than $50 about 10 years ago). The only thing you really need to do is call them up and talk to them. Answer the questions they are going to ask. It took about 20 minutes for me to recone my speaker, and that is because I really went to town cleaning up the frame before gluing the new cone in.
Their web site is www.reconingspeakers.com
I've been using these Alpines for the last 30 yrs in the front. Fits perfect.
https://www.crutchfield.com/S-corf9vPSvO4/p_500SPS080A/Alpine-SPS-080A.html
I also reconed mine. 3rd gens are a bit more critical for fitment than earliers I think.
Sure the recone kits won't perform necesarilly WAY better then the old stock unit being rebuilt on the same stock magnet/basket. Newers will perform better BUT... if you are not searching for a sound lever performance increase, you'll be just fine!