| Re: how to count gears?
You count gears the same as anything else. One, two, three, four, and so on.
No; no one here knows anything about rears.
To tell if it's an Eaton, you could start by looking for the Eaton logo or an Eaton part #.
To tell is they're 3.73s, you could start by counting the teeth, and finding out if there are 3.73 times as many teeth on the ring as there are on the pinion. Since there are always whole numbers of teeth on each (in a working one, anyway), the gear ratios are always the quotient of 2 whole numbers. In the case of 3.73, it's 11 on the pinion & 41 on the ring; 41/11 = 3.72727272727272....
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Numquam ponenda est pluralitas sine necessitate.
— William of Ockham, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi
Roughly paraphrased into modern English, and applied to figuring out what's wrong with your car:
The simplest explanation that fits all the facts is probably the right one. | 
