Bob
The reason they used 10 ohm speakers up front is that the two right hand and the two left hand speakers are wired in parallel which makes them effectively one 5 ohm speaker.
In my 1997 I have the Pioneer stereo and had the delco speaker .I replaced the speaker with 8 ohm speakers and reused the smaller tweets which are mounted right beside each speaker as well as the original speaker covers so it looks S it always did with no adverse effects it all works well.
Hope this helps
Eric