Older Gen 3 Glock 19 parts

I recently purchased 5 stripped Glock lowers and have discovered that at some point in the Gen 3 Glock 19's had some changes. The first thing I have encountered is the locking block. I think somewhere around 2011 Glock switched the frame design and the locking bock. The older models sits down within raised fins while the newer models are compatible with Gen 4 Glocks and sits above the frame however, there are no raised fins. I attached a picture which illustrates the locking block differences. My question for the forum is, are there other parts that are specific to this this age Gen 3 Glocks?
Thanks in advance for any assistance.
Jeff

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Originally Posted by Anoguous

I recently purchased 5 stripped Glock lowers and have discovered that at some point in the Gen 3 Glock 19's had some changes. The first thing I have encountered is the locking block. I think somewhere around 2011 Glock switched the frame design and the locking bock. The older models sits down within raised fins while the newer models are compatible with Gen 4 Glocks and sits above the frame however, there are no raised fins. I attached a picture which illustrates the locking block differences. My question for the forum is, are there other parts that are specific to this this age Gen 3 Glocks?
Thanks in advance for any assistance.
Jeff

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The left is also a steel block and the right is a MIM block
See the molding circle in the middle