Hello! As mentioned in my item description, I've been into 1966 Chevelle
SS396s since acquiring my first one at age 16, back in 1970. I've owned
several, and then later in life, became a used car dealer in the late 1970s,
thru 1980s, and then a Chevelle enthusiast, who has literally seen thousands
of 1966 Chevelle SS396s. In this 36 year experience with them, I have never
seen another true, 1966 with factory air, and a factory installed 4 speed,
other than my current one. I have seen probably 20 to 30 that had either the
4 speed, or the factory air added by someone after it left the factory. I
knew by this fact, that it had to be relatively rare, so, started digging
research back around 2000, trying to find factory build records. Well, there
aren't any complete factory build records from the 1966 model year, other
than the total Super Sports built, and a count of what options were ordered
in what numbers. There were tens of thousands of air conditioned cars, but
99.9% of them were powerglide automatic transmission equipped, as most
people that ordered 4 speeds, wanted raw power, and not a car loaded with
options like air conditioning, that would rob horsepower away from the back
wheels.
The I noticed an oddity about my 1966 Chevelle SS. It is a low mileage
(47,000), almost 100% original car, but it has a 10 bolt rear end
differential. Well, everybody knows that all Chevelle Super Sports had 12
bolt rearends, so I natually assumed that mine had been changed out by a
"salvage" unit. But under close study underneath the car, you could see that
mine appears to never have been ever tampered with, or any bolts ever had a
wrench on them. I was at a huge Chevelle show in 2001, and an old man who
had worked for GM back in 1966 in one of the plants that built Chevelles,
told me that an internal factory memo came out that specified that any
Chevelle ordered with both a 4 speed, and factory air, had to be built with
a 3:07 rearend, in an attempt to prevent the driver from "racing" the car,
and over-reving the air conditioning compressor, that wouldn't stand over
4,500 or so rpm. This was speced in an effort to prevent warranty claims on
the compressor.
Sure enough, my rear end differential is a 3:07 10 bolt rear end. It's the
only one I've ever seen in a 1966 Chevelle Super Sport, and only Super
Sports had the extra trailing arms to brace the rear end differential under
load.
I finally found a list of how many options were ordered on 1966 Chevelle
SS's, and only 33 cars got the 3:07 rear end.
Do I have proof of this? No, but I trusted the gentleman who worked at the
factory back then about that memo. Unfortuantely, he, nor I have a copy of
it.
What rear end differential do you have, 10 bolt, or 12 bolt, and what gear
ratio, and can you tell if it's original to the car, thru stamped codes, or
inspection of bolt heads, etc? Ridge in Tulsa.
