Fusion stereo replacement

I upgraded RA70 to RA770 and it was plug and play. Different size unit though. Used a faceplate.

Same here. Pretty much the same wiring, not all that much really has changed from that perspective.

just replaced the older kenwood from 2003 on my express. Did not need to re wire but did need to splice the wires for speakers and power. Grady was nice and used solid wiring harnesses, so it was not a huge challenge to do the splicing, as the wire harness was removable, and I could do the splicing and heat shrink at home, where I did not have to contort. As mentioned above, I needed to make a faceplace as the units were different sizes.

If your replacing a Fusion with a Fusion, I'd think you'd have the same dimensions if buying regular sized unit. I believe they have (2) housing sizes for the head unit. Check the specs online for the unit you have and the unit you are targeting.