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VIN Decode Question (AX). 1968 Coronet

68Coronet500!

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Hello,

I'm trying to decode my VIN to figure out what the gearing is in my 68 Coronet. I used the attached decoder however when it comes to the gearing, my tag simply has "AX" and the decoder doesn't have anything listed.

Any idea how to interpret this?
 

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What is underneath AX. Your 3 choices are generally
1
2
4
 
Show us the fender tag and we can probably help you. The number underneath the "AX" is the code. Mine is 68 for 3.55. I think all of the 68 R/T were 3.55 or 3.54.
 
Show us the fender tag and we can probably help you. The number underneath the "AX" is the code. Mine is 68 for 3.55. I think all of the 68 R/T were 3.55 or 3.54.
Standard for '68 would have been the 3.23 for an automatic and the 3:54 for a four speed.
 
Thanks guys.... looks like i've got the dreaded 2.76.

I figured this was the case as it's a slug off the line but sails pretty nicely at 90 on the freeway.

I want to put a posi rear end in and move to maybe a 3.55 or 3.73, any suggestions?

I drive it pretty much every day but would like a significant boost off the line.

To date, the car has headers, exhaust, 4bbl carb, performer intake.

One day, I'd like to do an engine swap but not quite there yet and figure the gears are a big part of the off the line issue.

IMG_3159.jpg
 
The number under the "A" is the code for the ratio.

Anything under the "X" (usually an "8") means sure grip (limited slip).
 
3.23 will be a huge change in how the car pulls away from a stop.

You have a 318 With a stock cam. So be careful with the rear ratio, it won’t go 70 mph and have much passing power with 3.73. Out of wind early.
 
3.23 will be a huge change in how the car pulls away from a stop.

You have a 318 With a stock cam. So be careful with the rear ratio, it won’t go 70 mph and have much passing power with 3.73. Out of wind early.
Thank you! That is what I was looking for. will 3.55 take it too far and limit the upside?

I haven't ruled out upgrading the cam and would be happy to keep the 318 if I can get more out of it but seem to be running out of ideas. I think the gears and posi will make a huge difference.
 
Thank you! That is what I was looking for. will 3.55 take it too far and limit the upside?

I haven't ruled out upgrading the cam and would be happy to keep the 318 if I can get more out of it but seem to be running out of ideas. I think the gears and posi will make a huge difference.

How to win friends and influence people...

"Posi" is a GM term. Mopars have Sure Grip. ;)

3.23's will make a difference and are easy to find. Beyond that, consider upgrading the power plant before going any deeper on gears. As stated above, you'll be winding up a small motor and running out of steam pretty quickly.
 
My bone stock except for duals 1973 318 with 65,000 miles, 904 auto and 2.76 gears will spin the tire from a standing start in the 3700 pound B body Satellite.

255/60/15 rear tires.

...and is still pulling at 115 MPH.

I don't think a 3.23 will hurt top end at all and I wouldn't worry too much about 3.55 other than maybe keeping the RPMs up higher than you may be comfortable with at highway speeds..

If your car doesn't already have dual exhaust, put them on. 20 HP give or take.

A four barrel is likely another 10-20-ish HP.

Now, a cam recommendation request will start the usual popcorn fest.
 
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Thank you! That is what I was looking for. will 3.55 take it too far and limit the upside?

I haven't ruled out upgrading the cam and would be happy to keep the 318 if I can get more out of it but seem to be running out of ideas. I think the gears and posi will make a huge difference.
That will depend a whole bunch on how tall your rear tires are.
 
A 318 can be made to run fairly well.... been there,done that... your limitation is the heads and cam. That correct combo, along with what you've already done, will be a pretty good street runner. Now, gears I'd probably do 3.23, but what diameter tires are you wearing in the back ?
 
I’m running a 275/60/15 in the rear and it won’t roast them
Then you need a bigger motor, lol. 3.55's will help a bit, but that is about as high as I would go if you do a lot of 70mph highway driving. I had 3.91's with 275 tires on my Road Runner. That really woke it up around town, but was real annoying on the freeway.
 
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