2046(s) withswing open boilerplate cover

I don't think that any 2046 had an opening boiler front from the factory.  But- since the boiler shell is the same as a 736, it's easy to substitute one if desired.  You could even install the boiler front with the Elesco feedwater as used on the 665-- that's what Lionel MPC did in 1980 with the Blue Comet.

Sorry about the posting mix-up.

I recently purchased two 2046 engines and tenders and upon second review, I found some interesting features that my original 2046 does not have.

It appears the two I recently purchased have many features that never came on the 2046 (only the 726 had them). The ornamental whistle and swinging bell are 726 features. I don't know if these are early factory versions of the 2046 or revisions done by a previous owner. The numbers on the cab are rubber stamped and show no previous alterations. The slot(s) in the shell (for the E-units) appear perfect and identical to my original 2046 in the photos. Both engines have magna-traction (as does my original).

Any ideas?

The boiler front and bell are easy mods that can be done with service station parts and a screwdriver.  The whistle involves opening up a mounting hole in the casting.  The one on the left in your photo also has hex-base stanchions on the pilot deck.  But the pilot assembly is a separate part, not integral to the boiler casting.  At least one of yours has the 3-pane window, which I believe is the earliest version of this casting.  My guess is that someone upgraded these at some point, but there's really no way to be sure.

I suspect you are right.

BTW, both of the modified 2046 engine have three windows.