I highly doubt those springs are a 3.5" drop.
A 3" drop would put most Civics & Integras on it's Nutz.
The lowest a manufactured spring would be is 2.75" drop tops!!......and that would most likely be a Ebay No-Name Brand.

Are you sure it doesn't say 350 which could be the Spring Rate?....Not the height.

Just trying to help you out a little.
If you could post a pic, I may be able to give you all the Correct Info on the springs your trying to sell.

-Jeff