Mini starter issue with slant 6

Hi buddies!

A few years ago, my starter died, and now that I'm trying to make run again my duster, I bought a mini starter, but I have a problem and I can't figure if it's possible to solve it. The pinion of the new starter it's different to the old one, apparently has different diameter and number of teeth.

Anybody has have that problem? Here are some photos of the starters






Saludos!