1979 Thunderbird Odd Rear Gear Ratio?

I have a 1979 Thunderbird that I've been building and i was looking for new higher gear rear end and the tag on the 3rd member says the ratio is a 2.75... which was not offered in 1979? The data plate also has a rear axle code of "2". I even got a Marti Report and it says the same thing, anyone have an explanation for why it has an unavailable axle from the factory or what it could mean?
 
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To me it seems someone before you ripped out the original axle and replaced it with what you have now. Perhaps in the past someone was a little too hard on it and ruined the original axle. Though what is your reason for wanting a higher gear ratio for the axle?
 
See, anywhere i look up they say the 2.75 wasn't an available axle from the dealership for the 79 bird, but mine was actually from the factory with it, and even the marti report says that it is real, but i don't know how it could be, since it wasn't even an available option. Could it be like a special order or pre production or test piece?
 
See, anywhere i look up they say the 2.75 wasn't an available axle from the dealership for the 79 bird, but mine was actually from the factory with it, and even the marti report says that it is real, but i don't know how it could be, since it wasn't even an available option. Could it be like a special order or pre production or test piece?
I think where you are looking up is incorrect. I would suggest looking up '77 or '78 since they both have the same 9" rear. Your information source may be looking up the 1980 model year which is a foxbody base. Not an uncommon problem between model years.

I would trust the Marti Report.
 
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I think where you are looking up is incorrect. I would suggest looking up '77 or '78 since they both have the same 9" rear. Your information source may be looking up the 1980 model year which is a foxbody base. Not an uncommon problem between model years.

I would trust the Marti Report.
I definitely trust the marti report, i just can't find anywhere saying that it was an option, which is why i thought maybe they were testing the rear end in the car. I want to know the spline count so i can get a new one that matches, which is why im trying to find out, you know what i mean? If you guys can find anywhere saying it was available it apprectiate the link, because i could find nothing. And also i checked for 77,78,79, and 80, and it was not an option for any, and 1980 and after didnt even use the 9-inch rear.
 
I have a 1979 Thunderbird that I've been building and i was looking for new higher gear rear end and the tag on the 3rd member says the ratio is a 2.75... which was not offered in 1979? The data plate also has a rear axle code of "2". I even got a Marti Report and it says the same thing, anyone have an explanation for why it has an unavailable axle from the factory or what it could mean?
What is your reason for wanting to change the gear ratio? Are you planning on racing it in the future or something? The trans and everything is set up for that ratio that came with it. Sometimes it's better to leave wellness alone & keep it original.
 
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