I have a 64?  gas 550 serial # 140-938-519 spec. # 45- 0037. I need to know if its a neg. or pos. grd. I need to order a new wirining harness hopefully to fix my not starting problem. Insulation is completely gone off wires from age and it started to stall.  I could adjust the wires (down the side of the block) and it would fire right back up. I thought they were touching the bracket they are feed though/attached to. I could slide them forward or backwards and the tractor started and ran great until it would happen again. Now it won't start.  I put off ordering a new harness because I didn't know what to order. Now I have to have it to get the Ollie running again.  any help is appreciated <!-- s:D --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt=":D" title="Very Happy" /><!-- s:D -->