Best rear end for a 3.4?

[58mark]

I've got a third gen, that I'm going to drop a 3.4 into. I'm going to build it up to about 200HP

What I'd like to do is change from my 3:42 rear end to something that will drop my RPM's on the highway. I have been told that with my current 2.8 that is a bad idea because the engine will labor too much in getting it going. With a 200HP 3.4, I don't expect that to be an issue, but I still want your opinions

This is my goal... Better MPG, and I don't care about being more sluggish off the line. Speed isn't my goal at all, but I'm hoping the extra HP will offset the different gears.
I also would like the rear disc setup and the 4th gen offset, because I've got my eyes on a set of deep dish y2k wheels

How hard is it to find a 3:08 rear end from a 4th gen? wasn't that the standard rear end on all v6 cars? does include both automatics and 5 speeds?

[96blackmaro]

Re: Best rear end for a 3.4?

What I'd like to do is change from my 3:42 rear end to something that will drop my RPM's on the highway. I have been told that with my current 2.8 that is a bad idea because the engine will labor too much in getting it going. With a 200HP 3.4, I don't expect that to be an issue, but I still want your opinions

Keep the 3.42s, it won't affect MPG all that much. Dropping to 3.23 may help highway a tiny bit 1mpg or, but you would you lose a tiny bit in the city.

This is my goal... Better MPG, and I don't care about being more sluggish off the line. Speed isn't my goal at all, but I'm hoping the extra HP will offset the different gears.

Not really you will probably gain mpg just from having more power to lug around all of that weight.

I also would like the rear disc setup and the 4th gen offset, because I've got my eyes on a set of deep dish y2k wheels

Not sure on this

How hard is it to find a 3:08 rear end from a 4th gen? wasn't that the standard rear end on all v6 cars? does include both automatics and 5 speeds?

You will lose MPG with 3.08s for both city and highway. My brother Firebird had 3.08s in it. It gained both highway and city mpg just by switching to 3.23s. 3.08s only came in auto 95-02 non y87 F-bodies.

[58mark]

Re: Best rear end for a 3.4?

how can you gain MPG in going from a 3:08 to a 3:23? wouldn't the engine ref higher on the highway in 5th gear?

what extra weight are you talking about? I'm going from a 2.8 to a 3.4. If anything the 3.4 is lighter.

[96blackmaro]

Re: Best rear end for a 3.4?

I didn't mean the engine was heavier. I worded that wrong. I meant the 3.4 will have an easier time lugging around the weight of the car than a 2.8 would. The difference in highway rpms is only about 100 from 3.08 to 3.23. It almost not noticeable. I can tell you my 3.8 gets around 30 mpg on the highway with 3.42s and at 75 mph it spins at 2500 rpm. If you want to increase mpg, do the free things: get rid of weight, and go learn some of that hypermiling techniques.

[ssms5411]

Re: Best rear end for a 3.4?

I agree keep the 3.42's.