Michael Carpenter, chairman of Southgate Alternative Investments and a former chief executive at Salomon Smith Barney, will be named as his successor, the company said on Monday.
Mr Carpenter was also on the board at CIT, a post from which he has stepped down, according to the GMAC statement.
The news comes about a week after the lender reported a third quarter net loss of $767m. GMAC is also likely to receive up $5.6bn of fresh capital from the Treasury, on top of $12.5bn borrowed from the US government since December 2008, as it has been unable to raise funds elsewhere.
But according to the statement, the timing of that injection (and potentially, the size) is increasingly unclear:
The board of GMAC has requested that the U.S. Department of the Treasury postpone its decision on the planned follow-on investment of Troubled Asset Relief Program funds in GMAC until Carpenter and the management of GMAC have assessed the current situation and can advise the board and Treasury regarding the appropriate amount and form of such funding.