I have two small block 727 inspection covers. One is one piece and the other is a two piece cover with the small piece that attaches at the bottom center. Can someone tell me what the reason was for the two different styles?

The separate cover at bottom center is to allow access to the converter drain plug without removing the whole cover.

Do you know if there was a particular year where one type replaced the other? Just curious which type was used before the other and when the change occurred.

I believe '68 was the last year of the separate inspection cover.

The transmission from my 1979 had a cover with the hole at the bottom. It wasn't the original transmission tho. I thought they got rid of that around the same time they got rid of the drain plug. I never paid much attention to it tho.