If you read my last reply carefully, the bit about putting an earlier RSA into a Gen4 was a direct response to Percussion's post, and my "Point" was to answer your question as to whether you could put a Gen4 RSA into a non Gen4.
You stated that you were going to replace the original RSA with a titanium one, and I enquired what your reasons were for doing so. Given that your knowledge of Glocks (based on your original question) is somewhat lacking, I was wondering what information you were basing your decision on.
This is precisely why I generally avoid posting here. As far as I am concerned, you can do whatever you want, It's your gun, and your money, so drive on. I'm done here.
Regards.
Mark