General Motors sold off a 51 percent stake in its GMAC financing operations this week in a fire sale that will funnel about $14 billion in badly needed cash into the ailing auto maker’s coffers over the next three years. A consortium led by hedge fund Cerberus Capital Management will transfer to GM $7.4 billion in cash when the deal closes sometime in the fourth quarter. GM will also get another $2.7 billion in cash…