This isn't the first old style pump with screws on the cover I've heard of so screws on the cover aren't definitive of a new style pump but no screws on the cover is an old style pump.

The rollers are the same size. They have to be since they use the same ramp on the IP timer. The old style has bigger bearings with the balls open to the engine. The new style has smaller bearings with the balls shielded, at least until it explodes

The first picture isn't clear enough to see the balls but I expect it looks like this -





Sixto
87 300D