GMAC Residential Funding Corp. Tweaks Collection Timing to Cover Shortfall in Fast Prepay Markets GMAC Residential Funding Corp. announced this week that it is revising the collection periods and compensating interest policy for its jumbo and Alt A private-label mortgage-securitization programs. The changes are designed to allow investors to recover the full coupon on the security during high prepayment scenarios, explained Eric Scholtz, managing director for capital markets at RFC. “Inclusion of curtailments