(04-02-2015, 01:37 PM)Thomcat316 Wrote: I'll definitely be keeping your suggestion about gearing in mind, too.  I regeared the Sonoma from 4.10 to 3.42, gained good highway mileage, and also gained a useable first gear....    Used to start out in second with the original gearing.  I'll be planning on driving the conversion around a while on the original gearing to be sure of the ratio I want to change to.  One thing I saw about the MB engines is that with the 606 peak torque is at 1600RPM, with the 617 peaking at 2400RPM.  My thought is that I'd plan on engine RPM at highway cruising speed in fifth to sit right to the north side of the torque peak, 1800 and 2600 respectively - is there an issue with that theory?

I don't know for sure what the 606 turbo torque peak is, but the NA OM606 torque peak is 2600 rpms
http://www.w124performance.com/docs/mb/O...606_NA.pdf

I daily drive a stock 606 turbo in a W210 and it doesn't drive anything like a 1600rpm torque peak. More like somewhere between 2500 and 3000. It does not push the heavy Mushmobile around very well at all at 1600 rpm.