A rare No. 4 Left-Hander?
Alas, no.  Just another nicely-done "improvement".  This one reversed the sprue-cutter and converted the
bullet mould to cast a hollow-based bullet.  
The bullet design appears to be a non-standard, similar to Ideal's 40188 Douglas
Sorenson design but with another grease ring.
This one is more in the "Blacksmith Salvations" sub-category. :-)
From the "use it up, wear it out" generation, this broken No. 4 in 38 S&W was brazed and returned to duty.  
Evidently it was a good job.   (Photos courtesy D. Elliott)
Owner's comments:
It looks a bit lumpy, but in my experience with such repairs, "lumps" are better left in place
where they don't interfere with operation or movement.  The mating surface has been cleaned up, and the tool
has obviously seen service since the repair - note the case rim impression in the braze at 6- to 8-o'clock around
the seat-crimp socket.  All in all, a much better repair job than appears at first glance.
An "Improved" Aluminum Handle 310
Photos and comments courtesy D. Elliott
Some happy soul had evidently wanted to "upgrade" his first-alloy-pattern 310 tool for use with 7/8" x 14 tpi
dies, disassembling it and discarding the lower handle half in favor of a new one hewn from a slab of 1-1/8"
Bored and threaded to the larger size, its grip fairly well contoured to match the upper one.  The pivot
operates smoothly and meshes well with the "upper", and a notch was cut out to receive the standard,
extractor hook - though there is no provision for a guide bushing - but it doesn't appear that the results
were satisfactory, as no further contouring was carried out and the Prussian blue spotting / layout
coating remains over much of the surface.
All the same, I couldn't resist trying it out with a .44 Special RCBS 3-die set and some fired cases I had handy.
Resizing (with the carbide insert die) was surprisingly smooth:
Although I limited it to the bullet seating area; and the case came back out with only moderate effort.

Decapping was a bit trickier, as the absence of a guide bushing made it a bit "fiddly" to mesh both the decapping
pin and the extractor hook, plus I didn't want to reset my lock ring (set up for my Rockchucker) and thus didn't
get full case mouth expansion.

Bullet seating (after a bit of chamfering and flaring by hand) went pretty well, though - again - I didn't want to
reset my die, so didn't seat it to full depth or crimp the case onto it:, so, with patience and a bit of fiddling the
modified tool can be made to work.

Uh-oh - we forgot repriming, for which the standard 7/8" die sets make no provision (since this operation involves
a shell-holder and priming stem or post on the press itself).  One could, of course, use one of the Lee or RCBS
hand-priming tools...

BUT, sticking to the modified tong tool, there is a solution:  Yup!  a 7/8" x 14 to 5/8" x 30 conversion bushing and
a 310 repriming die.  Which brings us right back to the starting point.  Nice try, but...
No, but an interesting conversion that took some effort.  The top of the mould was faced off and retapped
and drilled to accept a sprue-plate and a stop pin.  The same had to be done with the old base of the mould.  
One side of the block was drilled and tapped to hold a flat-based cavity former, probably to block off the
original base pour part of the mould.   Then a raised piece was added to the sprue-plate, evidently to fit a
specific pouring spout.  Note how the rim of the addition was cut to snugly fit the sprue-plate screw.  The
cavity appears to be for a larger caliber bullet.  It also looks like the bullet-seating stem and its lock ring were
modified/replaced as well.
Or, a Rare No. 6 "Left Hander" Marlin?
Of all the modifications listed in these "Blacksmith" pages, the one below made me cry out in pain.  Here is
a rare No. 2 in 38-44 T[arget] that is "improved" beyond redemption.

Some owner had a lot of time on his hands and got a brainstorm to convert an old "useless" tool to reload
the 38 Colt's Auto.  In order to do this, he had to ruin another tool (probably a 38 S&W) by cutting off the
fixed chamber and threading the top portion.  Then he tapped this chamber to take what looks like the
original bullet seating stem, and completely ruined this No. 2 by cutting off it's fixed chamber, tapping the
lower handle, and screwing in the modified seater.  The final degradation was to stamp "38 COLT. AUTO".  
(You have to wonder how well the rimless case was extracted by a hook made for a rimmed case.)
No. 6 45-90
This is a new one on me.  My best guess is that the owner needed to reload a 45-60 and wanted to keep the
crimp, so he went to a lot of effort to "lower the bar", so to speak.  
Looks like a probable two-piece set-up with the hook being one individual section and the lowered block the
other.  It would be interesting to see how it was secured as he couldn't have run a retaining screw up through
the middle due to the hook mechanism.
Seen on eBay.  On the surface, nothing much unusual, except for the missing bullet sizing plunger, which
wasn't needed for the Outside Lubricated bullet.  Probably sent that way from the factory as the pin that held
it isn't buggered up.
No. 4 38 Long
SURPRISE!  Another cavity cut, 22 or 25 from the
looks of it.  Note in the first picture that there was no
secondary hole in the sprue cutter.
Note also the hole for the hollow-point is off center.  
Between that and the rough base due to no sprue,
cutoff, it must have given some interesting shot
groups.  Then again, when the user saw he goofed,
maybe he just gave up.
Unusual placement of patent date.  I wonder if it
was also on the off-side of the tool, which was not
Another "Two-Fer" - A No. 6 32-40
This one has the secondary hole, which would have made for a cleaner base, but . . .
. . . another off-center hollow-point on the lighter bullet.  Too bad, the tool, if originally issued (I suspect it was,
due to the better workmanship) with the one hollow-point bullet would have made a nice collectible.