Wayne,
Wish I had a Dime for every time I've thanked you for your extra efforts !
If we ever meet dinner and drinks are on me.

From the CCCF: "CCNL 70 states that when Saginaw took over the Irwin Pedersen contract carbines were processed in 3 "batches". This featured carbine (1,775,265) is a "1st batch" as it falls between serial numbers 1,762,--- and 1,785,--- and it has all Irwin Pedersen parts.

I see the Featured IP you linked is serial# 1,775,265. Agree the 2 on the bolt looks very similar. Also a 2 on the side of the E279 Slide. Receiver marked M4 at the rear rail / right side.

Too bad we lost so many pictures, because a search here revealed another IP I believe may have also been a 1st batch.
A post by former member rokwell, (who I wish I could PM for the pics) described IP 1,774,10X. It also had a number of areas with a 2 stamp, including the bolt, op slide and a M2 among other areas. Receiver was also marked with a 2 on both sides.
Here's a link...... but void of pictures

https://www.milsurps.com/showthread.php?t=40210

I just tried opening my bookmarked posts by Mikey from New Zealandicon. He had shared a lot of great pics of early IP and S'G' carbines he'd ran across. But it now leads to no where, Damn that was a ton of great spotting now lost from a respected member of this forum the CC and the forum he headed up in NZ.

Appreciate everyone's input. I just ran across that Bolt listing and couldn't place it.

Great Weekend All,