Top speed is dependent upon the transmission in the truck, but 60 mph sounds low for a max.

You can change the gearing in the rear axle, but it won't do you any good without changing the front axle, too. Even when disengaged from 4WD, the front axle turns; and turning is required to lubricate the TC.

The W463 is the full time 4WD and it was introduced in 1989. Some good websites to find out more are:

http://www.graz.daimlerchrysler.com/20yg/e/start.htm
(works with MSIE only, not Mozilla Firefox)

http://www.g4rce.net/engl/index.html

http://www.pointedthree.com/disc/forums/forumdisplay.php?f=57

__________________
1973 280SE 4.5 (Sold)
1984 LWB 280GE (Sold)
2000 G500 NMLE - "Deep Throat"
2007 ML320 CDI (Sold)
2010 Porsche Cayenne S Transsyberia TipTronic (Sold)
2010 Audi Q7 3.0 TDI (Sold and Sorely Missed)
2014 ML350 BTC
2015 Audi Q7 3.0 TDI (On Order)