Yes, I have an early 1301 comp that does not have the spot for the 2nd washer, but you can purchase a new style plastic trigger group housing from Midwest Gun Works or other stocking Beretta dealer that does have it. I was lucky that also have a newer one to try.
But, I received mine and installed it. I noticed that the main (long) lifter was cocked off to one side (ejection port side) I am guessing one of the holes is off a little. But I thought maybe it was for a reason. I also noticed that the ramp of the shorter lifter that keeps the main lifter up to help reloads does not engage much of the release button, seems like it should be further back, it is easy to hit with shell bases and release a round out of the mag tube onto the lifter when trying to load, then your hosed. After I installed everything I hand cycled a bunch of dummy rounds through it and when you don't trip the shell release button while loading, it works pretty good. But the main lifter being cocked off toward the ejection port allows some of the rounds to get a little off center with the chamber and then they hang up on the chamber edge. Maybe I just received a bad one that got through QA and a good (straight one) would always center the round so it chambers. But the issue with the ramp not engaging much of the shell release button is a tough one to get around unless the ramp was moved closer to the trigger to engage more of the button.
If you have already ordered one of these I hope you have better luck than I have. I did take it out last Saturday and run about 40 rounds through it and had the same problems as when I hand cycled dummy rounds through it.
I have sent J. Kenny an E-Mail outlining my initial issues and will be sending another one tonight with pictures to see what he might suggest and if he will stand behind his product.
I'll let you know what I find out.
Jeff