Then, be sure when you install the 7 blade fan that it fits inside the shroud as it should (half in, half out) when looking from the top or sides. I see them all to often either way inside or not even inside the shroud at all.

If you are lucky enough to find the correct length shaft, you will not need the spacer shaft. If you do need the spacer, you can get them from 1/2" thick all the way up to 5" long etc. You can always buy the 5" alluminum spacer and cut it down to the correct legnth for your application to ensure that your fan rests perfectly. Then you just have to find the appropriate length bolts...