I just had my 518 rebuilt. It stays 1st gear. Even if I manually shift it into 2nd, it stays stuck in 1st. What could be the possible causes? Kickdown new an adjusted, shifter linkage is spot on thru all the gears.
I did my 340 with 518 attached from the top by myself. Wasn't that hard. I took trans mount out and when trans tailshaft got close to the ground I put a movers dolly underneath it. I had front end off the ground while I did it. I also have an old adjustable engine swivel that I kept adjusting.