Re: cost to rebuild
Around NE its $2400 for 4 cylinders , $3600 for 6 cylinder complete overhaul.
Try removing sparkplugs, bring ea piston to TDC , hold a dowel on top of the piston and rock it back and forth thru TDC. Roll it just past TDC and push the dowel down as you lock the flywheel in place, if theres slop you'll see it.
You could do it yourself for around $500....or less.