We had a '76 Chevy Impala in our family for 21 years. My parents bought it , kept it for 8 years and then we bought it from them originally to use as a second car.
As it turned out it assumed full use status very quickly.Great car, dead reliable, uber durable and we towed our trailer through the Rockies, western USA, Western Canada, the mid west, north western Ontario...it would start up in -25 to -30 or colder. A tremendous car. Twenty one years of very good service we got out of that car...and not easy service either.
The Impala had been bought new, from a dealer and just had the standard suspension. When we started towing trailers I decided to up rate the suspension. I had a commercial truck suspension shop recommend and install Moog Variable Rate coil springs.
What a transformation in handling...little to no sway...and it improved the handling significantly. Now a '76 Impala is a huge car...but with the addition of the heavy duty Moog coils...I found it was amazing how quickly it could go into a corner..again...very little sway..due to those upgraded suspension components.
A lot of people talk about mushy suspension, sway in corners with the old full frame, rear wheel drive American cars and to an extent that was true, because many customers wanted that lazy boy ride.
But when the suspensions were upgraded with heavy duty coils and leaves, bigger diameter anti sway bars front and rear, better shocks, better performance biased tires, etc...the results could be nothing short of amazing,
In fact American manufacturers had these up rated suspension available in the order book... but you or the salesman needed to know the order codes. With Chevies back then it was the F 41 suspension, police package 9C1, etc. I know, because I would find a salesman/ saleswoman who was willing to drag out the package catalogues where the little ordered heavy duty equipment was listed. I ordered a Chevy wagon with the heavy duty rally sport/ performance suspension...it came with DeCarbon gas shocks, heavy duty front and rear anti roll bars, larger /wider wheels, BF Goodrich T/A speed rated tires, etc.. I factory ordered a few cars like this
What a sleeper...it would surprise a lot of so called sporty cars...domestic and import in the corners . But you had to factory order these suspension packages for the most part, they weren't too common off the dealer lot and showroom. One salesman I spoke to was concerned after I told him to drag out the order catalogue for these suspension and big engine options...he responded by saying...but you won't want a car like this...it'll be a hot rod !
What I wanted was practicality...a wagon, 4 door sedan...with excellent handling and acceleration. I do believe that a car equipped thusly makes the driving experience safer....and as an additional benefit more satisfying to drive...read...fun.
These 'heavy duty' components were originally developed by the factory for extreme use...mostly police package use and were often available in partial or complete packages ...if you knew who to ask, what to ask for and where to find the codes.