A retail installment sale is a transaction between you and a dealer to purchase a vehicle where, you agree to pay the dealer over time. Call (215) 545-4830 - Danziger Shapiro, P.C. is dedicated to serving our clients with a range of legal services including Business and Corporate cases.View the terms and conditions of the Chapman Ford of Northeast Philadelphia website! The agreement of sale is strictly who's on first what's on second who are the players and that's what we're going to identify here. Let the Chapman Ford of Northeast Philadelphia finance team help you navigate the world of leases, loans, and purchase agreements.