[CPNE]

Here is an article you should read John. It should dispell your belief that the 73 tank relocation was safety related.

Link

For those not willing to read the entire article, I found this of particular interest:

GM TRUCK FIRE DEATHS AND INJURIES ARE AVOIDABLE

The tragedy of the GM Truck fire deaths and injuries could have been avoided and can still be reduced. Known technology exists in safer tank locations, breakaway fuel lines and safety valves, fuel cells and bladders and better packaging to prevent all fire deaths and injuries in crashes. In 1973, GM Engineers internally recommended to top management a level of performance for fuel systems in crashes such that "fuel leaks, should not occur in collisions which produce occupant impact forces below the threshold of fatality" -- i.e., if you survive the crash forces, you should not be burned by fires from fuel leaks.

This is the very principle which the US Army adopted in 1970 after suffering numerous burn casualties in helicopter accidents in Vietnam. In April 1970, Bell Helicopter changed production to use a crashworthy fuel system (CWFS) consisting of a fuel cells, breakaway fuel lines, and cutoff valves. "In the ensuing 39 months the Army experienced 702 accidents with CWFS-equipped helicopters with one very remarkable result - there wasn't a single fatality or injury due to thermal trauma." During the same period, helicopters without CWFS experienced 52 burn fatalities and 31 burn injuries in 895 accidents.

If GM Trucks had been built using design principles and technology known and available in 1973, then no one should have died from burn injuries in GM fire crashes. Due to heavy industry lobbying, NHTSA issued FMVSS 301 at levels far lower than what the auto makers could meet and what their own engineers said should be met. In a 1990 evaluation of FMVSS 301, NHTSA concluded that the standard had not reduced motor vehicle crash fire fatalities and injuries. FMVSS 301 should be amended to prevent fuel leaks and fires at crash speeds at which occupants survive as originally proposed by GM Engineers in 1973. Due to advances in crashworthiness since 1973, FMVSS 301 should be revised to preclude any fuel leakage in vehicle-to-vehicle crashes up to 55 mph front, rear and side impact.

GM Trucks were not even built to the same level of fuel system safety as that of their competitors. Both Ford and Chrysler installed the gas tanks inside the frame rail because of concerns over fuel leakage and fire in side crashes. As a result, the incidence of fatal injury in side impact fire crashes where death is caused by fire is 3.5 times higher for GM than Ford and 4.7 times higher than for Chrysler. Our analysis indicates that $465 to $910 million of the $2 billion cost of GM Truck fires to date is attributable to fuel tank location.

By recalling the 1973-87 GM Trucks with side saddle gas tanks to remedy just the fuel tank location, we could reduce the future crash fire costs of these trucks by up to $370 million. The repair remedy in the recall could be to move the tank inside the frame rail or install bladder lined tanks and protective cages outside the frame rail as GM proposed but never implemented for its 1983 Trucks.

It's interesting the "bladder lined tank" concept is afforded by simply placing the tank inside the cab structure.