How about the 3131?

It´s just like the 3186 that Elmar suggested but without the nonsense date and 24h-hand functions!

The cal. 3131 is the most basic of the modern movements, includes all the goodies like a balance bridge instead of a balance cock, a balance wheel with screws and the parachrome bleu hairspring.

That´s about all I want from a Rolex movement.

Cheers-
N.