The shaft measures 3/4D x 3-1/4L , 3/16 key. We have thoroughly degreased & power washed this really nice little engine, and it is in really good condition. Not only is it ELECTRIC START (120vac) but has a backup RECOIL START as well..This powerfull 4-cycle engine is PERFECT for that go cart or mini bike project. Or use it to replace that blown up snowblower engine from last season.. The item "BRIGGS 5.5HP- HORIZONTAL SHAFT ENGINE ELECTRIC & RECOIL START" is in sale since Thursday, August 16, 2018. This item is in the category "Home & Garden\Yard, Garden & Outdoor Living\Lawn Mowers\Lawn Mower Parts & Accessories". The seller is "vintage-tractor-phil" and is located in Rochester, Michigan. This item can be shipped to United States.