B.C. makes good sense. However, here is why I have decided to install a 2.47:1 in my 1978 300SD.

Before I switched jobs, I was commuting 1,100 miles a week to work, all of it freeway, with roughly a 2.5 hour drive each way.

If I drove 60-65 mph religiously, I could net 30-34 mpg over several tankfuls of fuel. If I drove 70-80 mph, the car seemed 'peppier' and happier at higher rpm, but my fuel economy dropped to 22-25 mpg.

In my case, I figured the 2.47:1 would allow me to run with traffic (at 75-80 mph) and keep my rpm's where they seem happiest (2200-2500) from an mpg standpoint...

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership