What are the details of your Blazer?
If it has a standard Holley, probably any center bolt air cleaner would fit. I'd look through the junkyards if you want a stock unit. Myself, I'm heading to a junkyard hopefully soon to find a unit off a TBI 454, which I hear has a larger element than the TBI 350 unit (center bolt) I have now. I believe either of those would fit, with minor modification, to a Holley.
Clay