1973 SD Transam 4 spd 1 of 72 built

[L78steve]

Originally Posted by njsteve

3.42 was the rear end ratio for stick cars and 3.08 was for the automatic cars with or without A/C. (No A/C allowed in stick cars). All the four speed transmissions were the same internally and were no longer built by Muncie in 73.

You are quite correct- these cars are scary fast. And to think that they accomplished all this with 8.6 to 1 compression!

If there is one version to have of a SD455, it would be a stick car. (Unless you're old like me and need to be refrigerated and have the shifting done for you) :-)

The 3.08 was for auto with A/C. Auto or stick can be had with the 3.42 w/o A/C. I had a 74 SD Auto no A/C with 3.42, unless 73 was different for the auto and 3.42.

[njsteve]

That is correct. From personal experience I think the autos run better with the 3.08 rather than the 3.42.

[black69]

Originally Posted by njsteve

That is correct. From personal experience I think the autos run better with the 3.08 rather than the 3.42.

Here is some info out an attached link on the performance related to rear end ratios:

Where the SD-455 Trans Am dropped to low-14 second quarter-mile range was when it was equipped with both the automatic transmission and air-conditioning which gave it a mandatory 3.08 rear axle ratio.

Link of reference:

http://www.firebirdnest.com/index.ph.../9-1973transam

[black69]

Hey, I think a relative to this car just sold.
http://www.legendarymotorcar.com/inv...55sd-1178.aspx

[70post]

It is a cool car. If it's the same car that was in the Austin, TX area, now sans the Screaming Eagle decal on the hood, then I know it well.

[black69]

Originally Posted by 70post

It is a cool car. If it's the same car that was in the Austin, TX area, now sans the Screaming Eagle decal on the hood, then I know it well.

I agree, it is a cool car!