The rear bar was only F41. Our 396 car has the F40 option and doesn't have the big front bar. I think that the F40 was perhaps just stiffer springs and shocks. I added the rear bar to our other Chevelle shortly after buying it. Someone had also added the rear bar to our 396 car as well. These cars needed all the help they could get in the handling department. That Chevelle sounds like it would be well worth fixing up.
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Chevelleless after 46 years......but we did find a low mileage, six speed, silver 2005 Corvette. It will just have to do for now.