It sounds like a 3.54 is the way to go.

Chuck

What kind of results do you have had with 3:9 + 5 speed?

What kind of results do you have had with 3:9 + 5 speed?[/quote

For Motorway driving with a five speed and 3.9 you would want to be in fifth I would think.

Personally I prefer to stay in fourth as its direct drive through the trans. so I chose a 3.54

Less wear on moving parts through the trans.

I would go for the 3.54, but depends a lot on your traffic conditions and style of driving. If you liked the 3.3 then the 3.5 is little different.

Back in about 1973 when I wanted to go with a 5-speed in our 6/70 Z, there were only two options:

(1) to swap in a 5-speed out of an SRL311 2-liter roadster, or (2) bite the bullet and spend the

money on the HD Competition Dept unit. I bring this up only because the internal gearing of the

transmission itself is going to affect your final drive ratio. Since I was doing a lot of highway

driving at the time, I wanted to go for fuel economy by keeping the 3.36 differential. The final

drive ratio had been 1:1 with the 4-speed, so I figured the 0.864 5th gear would give me a nice

overdrive.

The problem that evolved was that with a high ratio (low numerically) differential, I basically had

to ride the clutch just to get the car in motion. So much for economics: clutches were more

expensive than gas at the time. So I went ahead and got a 3.90 Comp Dept limited slip.

Multiplying the 0.864 times the 3.90 differential ratio brought me right back to a 3.36 final drive

ratio, so after considerable expense, I was right back to where I had started.

Except that I now had 5 gears to choose from to better suit the driving conditions of the moment.

And for a guy like me who has always enjoyed shifting his own gears, the additional gear gave me,

in effect, 25% more enjoyment.

All Z Best,......................................Kathy & Rick

Thanks for all the input!

Go as low az you want, you'll have an OD for the highway and still get decent MPG. it might make 1st gear a little more useless, but these engines are capable of rpms, so why not use them.

3.54 's with my t-5 in OD was about ridiculous unless you wanted to cruise at 85 or more. Also, with anything other than stock exhaust that has any drone at 2200-2500rpm - you will be in the drone zone at cruise.