I am pretty sure they will fit but I want to be positive they will...so will they? they are coming from an Si into another Si. thanks

 

between 90 and 91 and think thats the same. i think they're the same for all models.. cause the dashes i dont think are any different in shape.. just more switches for other goodies. my 90 dx dash looks just like my 91 Si, so i wanna say yea

 

is there anyone on here that has an 88 or 89 and a 90 or 91?
I am now wondering if the vents would be the same for the two.

 

I have a 90 and a 91. they are the same. I just parted out an 89 and it was the same as well. I hope you mean the center vent where the clock is.