ap photo U.S. Postal Service carrier John Graham drives a 28-year-old delivery truck while making’s rounds, Wednesday in Portland, Maine. Hundreds of the aging trucks were reported to catch fire in recent years.

PORTLAND, Maine — Postal workers thrilled at the prospect of making deliveries in modern, comfortable and environmentally friendly vehicles are soldiering on in their aging, spartan trucks.

The primary fleet of vehicles — dating to 1987 — was due to be replaced under a new contract but the winning bid for the new trucks is being challenged. That means the delivery of new trucks set for 2023 could be delayed.

“The longer this drags on, the more lives are at risk,” said John Graham, a postal carrier who operates one of the old vehicles in Portland, Maine.

Most workers don’t care which model they get. They just want something that’s safe.

More than 150 of the current vehicles have caught fire. They lack adequate heating and cooling, they deliver poor fuel economy and they’re becoming difficult to maintain.

The Grumman Long Life Vehicle delivered on its name. They went into service from 1987 to 1994 with a promise of a 24-year service life. The oldest of them have survived about 34 years of grueling use on the daily mail routes from snowy Maine to sunny California.

Most postal carriers will tell you they weren’t so great even in their prime.

They’re built on a General Motors chassis with a body provided by Grumman and they’re powered by a four-cylinder engine that was supposed to deliver fuel economy — but in reality provides about 9 miles per gallon (4 kilometers per liter) on stop-and-go routes. Missing are modern safety features like airbags and anti-lock brakes.

A glaring fault in Maine’s cold winters is inadequate heating.

Even worse is the lack of air conditioning that allows temperatures to soar to dangerous levels inside the vehicles on hot summer days. A postal worker died from a heat stroke earlier this summer during a heat wave in California.