In The following years Flxible increased production adding the assembly plant in Delaware and also several models of buses, among them the Starliner, the Hi-Level, the Flxette, and the FlxLiner. In 1961 Flxible introduced the "New Look" transit coach and was accepted as an industry standard for the next 18 years. The coach featured a rear mounted Detroit Diesel, an enlarged reflection free windshield, double bay passenger windows and fluorescent lighting. These coaches were later equipped with wheelchair lifts and special features to make the coach more accessible for handicapped and elderly patrons. 1964 brought to an end to production of funeral cars and in 1967 the 29 passenger StarLiner coach was phased out. The Flxliner was discontinued in 1969 and in 1976 production of the Flxette ceased. The last "New Look" coach produced was delivered to the city of Akron Ohio in October 1978.

In 1970 the Flxible Company was acquired by Rohr Industries and pioneered development of a new transit coach that evolved into the 870 Advanced Design Bus (ADB). The "870" was designed to meet Federal accessibility guidelines for handicapped individuals. In 1974 the corporate headquarters and final assembly were moved to Delaware, the Loudnville facility maintaining manufacture of sub-assemblys, and parts.

In 1978 Flxible again changed ownership. Purchased by Grumman Allied, Flxible became known as Grumman Flxible Corporation and in April 1978 the first 870 ABD rolled off the assembly line. The ABD 870 features aluminum extrusion sidewall construction with no external fasteners, 40% fewer parts, lighter weight, lower floors, more window area and many other improvements over the previous model. Grumman Flxible quickly accumulated an order backlog of over 2,500 units from 28 transit systems including an order for 1,013 ABDs for New York City. In 1981 the company introduced the new Grumman Metro which featured nearly 100 changes throughout the bus including a 6V-92TA engine and improved steering and suspension. The first order for 20 went to Spokane, Washington in early 1983 Flxibles 70th year, and in the same year Grumman Flxible was again sold to General Automotive Corporation who continued the line until closing operations entirely in late 1995.