Is this the math for the rpm change?:

2.65/2.88 x given rpm = new rpm?

So:

.92 x 3400rpm (at 80mph) = 3128 ?

While that change would be welcome, I'm looking for a lot more than that...I'd like to get down to maybe 2500 rpm at 80 mph.

I don't know much about these things, but my 300DT revs seem high for 80mph...esp for a large car which typically is designed to loaf...seems to me, just intuitiuvely, that the rear end would be higher than 2.88.

What about the 2.47 that I've read about? Is that available for my car? That would potentially give me 2915...hmmm...nuts...again, welcome, but not the change I'd like to see.

Thanks...