Does anybody know if there's any little difference in the 88 and 91 si suspension? Can I swap my 88 suspension to the 91 without having to customize my axles? Well I did this swap and I have a problem with the passenger side axle it seems short like a 1/2 inch to an inch. I'm able to move the car, I haven't tried driving it yet but I'm afraid that the axle might pop out when I turn.

 

Yes there is a minor difference search the EF forum it'll explain it quite well.

Also the trim will matter (hf/si/std) for axles. Again the EF FAQs will be able to cover this with tons of details.