Idrive a 71 142E with an M41 and a 4.10.1 rear end. When I had the limited slip rebuilt recently, I went with the 4.10.1 instead of the 4.30.1. The decision was based on highway driving preferences. The car was a rocket 20 years ago with a 4.30.1 rearend when I autocrossed it.
The 1971 142E alone was provided with a 2 inch drivetrain which can handle more torque than the other 140 setups of the time. The same U joints that are used for the 164 6 cylinder.
I have an IPD street cam with a lightened flywheel. I have double valve springs with a balanced engine rebuild. My last gas milage on the interstate at 75mph was 25 mpg. The car is lowered on IPD springs. It is a wonderful highway cruiser with plenty of high speed acceleration for passing.
I would make your selection of the rear end based on what you want from the car when you drive it. If you want stoplight acceleration and faster low speed response from your car, go with the M41 and a 4.30.1. If you want to have an outstanding highway cruiser, go with the M41 and a 4.10.1
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Antique Swedish Steel (Never Rusty) Silver 71 142E