Jeff,
You've got me on the speaker phasing question! Although I haven't tried to hook another speaker up to an 845; some of the early C730s have external speaker strips too, in addition to the phono jack and switch. The MJ uses an RCA-type push connector to connect its stereo speaker; the same style used for the phono jack.
Come to think of it, I haven't tried a turn table either...
To answer your other question, I did a bit of looking and discovered the speakers in the MJ1035 are exactly the same ones (same part number) used in the 845...or at least, the ones I have. Both radio and speaker cabinet use the same size; each are roughly 8" in diameter and uses one tweeter; an identical set up to what Zenith installed in the 845.
Here's the stereo speaker box:
And a look from the outside:
Here's at peek at the MJ 1035's speaker and a bit of its chassis:
...and finally, the whole set:
This MJ arrived this week and it is a really clean example. Don't ask how many I have now! My wife may read this!
As for the sound and reception differences, I have no explanation now. I remember reading somewhere (on another antique radio forum) that the MJ had cheap speakers, and that compromised its sound. I don't agree with that knowing what I know now, but can't explain why the radios sound so different. The MJ 1035 is warm and mellow, typically excellent Zenith tone adjustment and can be played quite loud before distorting.
I don’t want to say the MJ has poor reception because that wouldn’t be accurate, it is excellent, but doesn’t ‘seem’ to be on the same level as the 845, which most (me included) regard as extraordinary. The big MJ lacks the punchy bass reflex of the 845 table radios and the separation; I was listening to a Lovin’ Spoonful song the other night (“Younger Girl”) and heard instruments that I never noticed before. Just a truly great and special radio.
Time permitting, I may try some other speakers on the MJ, but bottom line; the 845 is a better radio. If dual speakers and stereo separation is important to you, find an MJ and enjoy; it's a fine set. They are still affordable and if you are really serious about collecting Zenith, you must have both. The MJ 1035 is the 'zenith' of Zenith table radios…even if it isn’t the best Zenith table radio.