In the interest of getting the best MPG out of a 95-940na which the manual indicates has a rear gear ratio of 4:10, & lists the turbo as having a taller gear of 3:73 . Is it worth the time, trouble & $$$ to do the swap. With the 4:10 I'm right around 3K rpm's @ 70mph. Don't want to lug the engine though. With the 4:10 I find myself using the OD switch on certain road conditions to keep from lugging the engine.

On my old BMW I've already swapped the stock 3:46 diff. for a 3:25 limited slip. I think I get about 2 extra mpg cruising mileage. Hard to believe this long heavy 635 with a big 3.5L engine, gets better mileage than the 940. The bimmer is a 5sp. & it did change the gearing a little bit. Find myself using 4th more frequently on long climbs, but with a manual it's easy to stay in an rpm range that doesn't lug the engine. This engine doesn't come on cam until around 3K.

Anyone done this? Thanks Dave