I have a model 71, 1956 or 57 manufacture. I want to install a Lyman 56 on it. Can anyone tell me the difference between a 56A and a 56LA. From what I've read the 56LA was for Marlin and the 56A for Winchester however after finding a 56LA it appears it will work on my rifle. So what is the difference between them?

I have had both, and my clouded memory says the width of the stem. across the top of the receiver is a bit shorter.

I haven't ever tried to put a 56LA on a model 71. If it will fit, then it will probably work. I thought the Marlin hole spacing was different but the difference is probably only the width of the arm that goes over the top of the receiver. It is probably a little shorter than the 56A.

For the "purist", the 56A is actually not the period correct sight for a 1956/57 gun. I believe you want the Lyman 66MA which is actually harder for ME to find than a 56A.

the hole spacing is the same.