The Shell 4000 was the worlds longest, most grueling rally in the 60's, and the only FIA sanctioned one in North America.
For the rally cars, Chrysler chose the 413 with 360 horsepower and a simple four barrel carb backed with the Torqueflite three speed automatic transmission. Both cars were two door hardtops and set up by Carl Prueths for rally racing with complete chassis protection using 3/4 inch welded steel plate on items deemed to be in danger including shock absorbers, engine oil pan, the K frame cradle, rear axle carrier and the leaf springs. A roof lamp was mounted providing high power wattage to light up the road ahead and help set up the car for turns. Even the tires and wheels were heavy duty. The 300 usually ran 14 inch rims with nice cushy road tires. These rally 300s came with 15 inch weld reinforced steel wheels with special 9.00x 15 inch Goodyear non expanding braced tread tires imported from Belgium.
The drivers were Gene Henderson with Fred Browne as navigator and the second car had Terry Sumner and Roger Bohl as navigator. Both cars were painted white with blue stripes in the center.
Starting in Vancouver, to Calgary, Regina, Winnepeg, along the north shore of Lake Superior, Chrysler proved that if soundly designed and properly equipped, even a Pentastar Panzer will be a competitive rally car..
The rally was annual from 1961 through 1968, then Shell ended it's participation. A similar rally was held again in 1971, 1994, 95, and last in 1997. In 2009, Napa had a 500 mile rally.
That 1st rally even had a V12 Rolls Royce, and it weighed 7000 pounds
In 1967, a Barracuda (340, 4 spd) came in 2nd, and the following year won, the Shell 4000. The 1st time an American manufaturer won the World Championship Rally. http://justacarguy.blogspot.com/2016/10/the-winner-of-1968-shell-4000-mile.html