The Grumman 870 bus was one of two advanced-design buses (the other being the Rapid Transit Series (RTS II) developed by rival General Motors and later taken by MTS).

[3] Under Grumman ownership, Grumman-Flxible (as the company was called at the time) received a major order of buses from the New York City Transit Authority along with other agencies.

The NYC Transit Authority order, built in 1980, is notable because this batch would expose the design flaw in A-frame noted during testing: the inability of the bus to withstand wear and tear in cities where potholes were a problem, forcing all 870s built until that time to be taken out of service beginning that December while repairs to the A-frame were made, which would cost Grumman $7 million to fix.

[4] Eventually, Grumman was forced to sell the line to General Automotive Corporation in 1983 for $41 million, a 25-percent loss after developing the "Flxible Metro" which addressed all of the shortcomings of the Model 870 in 1982.

[10] The Grumman era of production would result in a number of lawsuits related to defects in the A-frame of the 870, involving either Flxible's former owner Rohr or the Metropolitan Transportation Authority of New York.