Kewl! My blade on my 147 has the QA as well, but the bracket that mounts to the tractor is long enough it has a hole in it that lines up with the frame so I bolt it just for added insurance.
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Daniel G.
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(May 1970) 147 w/an IH spring assist, 48" deck, 42" blade, 1969 73, #2 trailer, 10" Brinly plow and (on loan) Dad's #2 tiller.