I needed spark plugs for my Ford 850 tractor, I forgot the plug when I went into town so had to cross reference to what they had. I ended up getting an Autolite 2635. While putting in the last plug I checked it against the old one and noticed that the Autolite was about 1/4" longer than the old plug. I finished putting them in and started the tractor up and it ran. I didn't hear any tapping or unusual noise so I shut the tractor off and pulled one of the plugs and it looked fine, wasn't collapsed like the piston hit it. My question is should I replace with the shorter plug or will the Autolite's be fine?