3.73 gears from a T-bird Turbo Coupe?

[JoeDaddy]

I've got a turbo coupe rear end that has 3.73 gears in it. My father-in-law, who is pretty good with cars, says those will go in my 96 mustang with no problem. I belive that they are both 8.8 rear ends, so I assume that he is right? Is this a pretty easy unbolt from one and bolt into the other?

Now, he is trying to talk me out of it, because the gas milage will suffer. How big of a drop should I expect? I get around 22-23 now. I generally set the cruise at just under 60 (seems like its about 1800 rpm), and am not on the highway too much.

Searched on the turbo coupe question but not on the gas milage question. I'm at work, and not much time.. Many sorrys.

Thanks

 

[wmburns]

Might be handy to mention what MY is the donor. Why? It makes a difference if the donor is IRS or straight axle.

If the donor is IRS, it sure seems like a waste to ruin an IRS axle that is surely worth more than the gear set within.

On the surface, this seems like a risky way to get a set of 3.73's. Especially since for all intensive purposes, the job of transplanting the gears is almost the same labor as rebuilding it. For that reason what ever you decide to do, add a bearing rebuild kit to this project.

There are TONS and TONS of posts regarding the pros/cons of 3.55, 3.73's, verses 4.10 rear end gears. Some ppl will say it hardly affects the gas mileage at all. Others will say it has an effect. Still others will say that 3.73's are not low enough to have that much of a proformance improvement.

MY ADVICE. if you are concerned about gas mileage at all, then this is not the project for you.

 

[JoeDaddy]

MY is model year? If so, this one came out of an 87 turbo coupe. They were all straight axles I belive.. The 87 & 88's had disc brakes in the back..

It all started with I thought my mustang did not have the trac loc in it (due to some fantastic one wheely peelys), and he said we could take the one from the turbo coupe and put it in the mustang. I then said, if we were gonna to that, myaswell put in the gears too. When I just changed my shocks, I looked at the axle tag on the mustang, and it does say 2L73, so the trac-loc is just worn out.. I was just wondering how big of a project this is.

I'm not overly concerned about the milage. Just don't want to go from 22 to 15.

Thanks

 

[Maxpowers]

You will never see that low of gas mileage. I have 4.10's in my car and the lowest I have seen is 19 mpg.

If you are planning on upgrading, buy yourself the FRPP carbon discs. You might as well change the bearings while you are in there.