The trans will have the VIN # stamped on it somewhere, and that will tell you if it is in fact the original for the car....sometimes it will be stamped on the tag, but then again, it could be just about anywhere.
Unfortunately, if those are the numbers you got from the metal tag on the right rear of the trans, it's for a '75 model car(modified Julian date of 480...sometime in April), and not even a Corvette, at that. The number for your car should start with
70(for 70 year model), and then it would have either a
K(for 350 engines) or a
S(for 454 engines).
So, your's would show
70Kand then three numbers representing the (modified)Julian date of build.
The "Modified" Julian date is a little hard to figure out, since there are only 365 days in a year....but...here's how it works(some carbs are dated the same way).
The Julian Date would start on the day that production started on the cars, not the transmissions.
So, say that production started on Aug. 21st, the trans build date would be
233, meaning the 233rd day of the year. Then, the dating would continue
from there until the end of production. So, a build date of
385 would mean Jan 20th(365 + 20).
So...all of that just to say that your car does not have the original trans in it...
______________
Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"