Pretty simple I bought a used Husqverna ...CHEAP, started going through it gonna give to son-in-law, found out it is a MIX of years and parts from everything under the sun and most all wore out, no problemso Im replacing bushings and run into the from axle 2 bushings no big deal, pulled the bolt that holds it expecting a lot of wear and there is none. the bolt is a cap head 7/16 but the shaft on it is smaller in diameter that the thread, thats whats causing the back and forth on the axle- has to be the wrong bolt- anyone??? Should these have a thicker shoulder on the bolt that the thread?
Take the model number for under the seat and go to this site to find the correct parts you need. You said yourself that it was a mix of parts so this is what we will need to do. https://www.partstree.com
#3
StarTech
First you don't measure hex screws by the wrench size; unless, you using the open end to get a quick estimate of the shaft size. Hopeful you are referring to the screw size as even a 3/8" normally has a 9/16" head and the 7/16" has a 5/8" head.
Second the YTH1842 came with two different hex screws depending on the variant. One was a 3/8" and one was a 7/16". Actually the early version 3/8 was a carriage bolt which may been replaced with the hex screw by a previous tech.