I have a Colt R6601, it is an A2 configuration (it is an HBAR, but I prefer that to the skinny government profile) but has no bayonet lug. My understanding is that these rifles, which were made in the years leading up to the ban, came from mix-n-match parts bins. My dad purchased it in 1991 I believe, and one of his friends got one too (same day and same dealer). They are very different rifles though! Only a few serial numbers apart, they differ as follows:
Mine:
Large take-down pin
Standard fire control group pins
NO sear block
Flat-side lower receiver (no fence around mag-release)
His buddies:
Standard take-down pin
Large fire control group pins
Sear block
Fenced lower
I believe the R6601 is the last non-compliant A2 style rifle that Colt made. The receivers are grey in color and they have no bayonet lugs on the front site base, although all the other "evil" features are still present.
I love mine, I remember when my dad brought it home when I was 6 or 7, and he gave it to me when I turned 18. It has never hiccuped, jammed, or malfunctioned in any way.
You can find them for sale every now and then, and since you already have a few Colts, you might as well add to the Pony stable!
Edit: Just caught the bayonet lug comment you made, but the flash suppressors are still there!