Hi Speedy, Bushie and Aussietrev,
They're all interchangeable from a 9 or 10 cubic inch briggs. 148cc or 158cc motors basically. 200 series, 220 series, classic 35, sprint 375, sprint 40, quattro 40, 450 series, 500 series and so on just to name a few. They'll all fit the 450 series you have there. I have about 20 here, if you were closer i'd give you one to use and one to keep as a spare.lol