Generator vs Starter

OK, so I got another 10XL. The new one is a '72 and my original is a '71. Which leads to a general question...why was the switch made from generator to starter with internal alternator? It strikes me that the generator arrangement is more reliable. Can I use my generator as a starter on the newer engine? The newer engine is the one that runs better, but the starter sounds like a metal muncher and wants a lot of juice to crank.

I suppose it is a long shot, but what other changes happened (besides paint color) in the one year separating the two tractors?

Any thoughts are greatly appreciated...