I don't know if the pickup system would clear the Blazer gas tank???
I'm just finishing installing Hooker Headers 16527HKR, a 2-1/4" mandrel bent regular steel exhaust system on my '71 Blazer 4x4:
http://www.holley.com/HiOctn/ProdLin...ExhstSyst.html
http://store.summitracing.com/defaul...7HKR&x=16&y=13
I'm very happy with it except it was not made to work with the factory T-case skid plate and extra crossmember. I had to cut the front pipes in half and add a 12" straight extension to get things to clear.
My only other irritation is that it has oddball 2-1/2" header collector flanges which I had to cut off since my headers have 3" collector flanges.
I believe they also have 2-1/2" systems.