I just noticed...

[Forty Rod]

I've had my Henry and '66 since 1987, neither one has more than a box or two of ammo through it. (Usually shoot the '73.) 

Just yesterday I noticed that the '66 has three screws in the left side of the receiver that aren't in the Henry, and one on the right side.  One of those on the left goes all the way through, but none of the others do. 
Both have hammer and lever pivots, but these are in addition.

What's up with all that?  I always thought, if I thought about it at all, that they were pretty much identical except for the barrel / magazine assembly and the loading gate.  What have I missed?

[Joe Lansing]

    My Uberti '66, purchased in '68 has 3 screws on the left side: lever; side plate; and hammer. On the right side is a loading gate screw.
The trigger is pinned in, and there is the saddle ring.

                                                             J.L.

[Forty Rod]

Okay, loading gate screw.  Got that one.

#2 screw goes clear through from let to right just below the bolt at the rear of the side plates.  Looks like it holds the rear of the side plates in position as they aren't dove-tailed on the rear.

#3 and #4 are at the rear of the frame on the left side below the rear of the hammer, parallel with the center line of the butt stock, 1/2" center to center, and different sizes...larger to the rear.

#5 on the right side at the rear of the side plate and about centered top-to-bottom about 1/2" forward and 30 degrees down from the #2 screw above.

Guess I'll ask Rowdy and White Lightnin'.  They've had these apart in the last few months.

'Tis a befuddlement.

[Joe Lansing]

     Your #3 and #4 screws are right where my saddle ring goes. My carbine has 2 holes at that same location for what amounts to a "u" bolt held in place by a "nut" inside the receiver. The saddle ring loops through the "u" bolt. Maybe your rifle was assembled with a carbine receiver and those are filler screws.

                                                        J.L.