First, are we talking about a manual or automatic transmission?

manual

I've done it both ways, though not on a flat head, and have found that, at least in reassembly, it is much easier to treat the engine and trans as a complete unit. It is so much easier to mate the two outside the confines of the car than inside it's envelope.

While I would still pull engine and trans as a unit, the other alternative would be pull the drive shaft, undue the shift linkage and emergency brake, support the transmission and drop the rear cross member, undo the 4 bolts holding the transmission to the bellhousing and remove the transmission. The rear of the engine will also need to be supported as the transmission is pulled to prevent the engine tilting back and breaking the motor mounts.

As supercuda says, "... it is much easier to treat the engine and trans as a complete unit. It is so much easier to mate the two outside the confines of the car than inside it's envelope...."

This quote from qualityengineeredcomponents.com:

"Circa 1959, a bellhousing was used, mostly on the Dodge 230, that was the correct depth and had an useable mounting face for the NP230 and the A-833. The mounting depth is critical in the application due to the length of the input shafts. This bellhousing can be identified by the fact that it also has the v-8 block bolt pattern. Depending on the transmission selected there will very likely be a need to make modifications to the bearing retainer register interface as well as providing proper transmission mounting bolt hole locations.

It is also referenced on vintagepowerwagons.com.


R.

Dodge has made some strange specialty parts through the years. in the mid 60s, that made a slant 6 727 (and a matching manual trans bell) that also had a LA small block bolt pattern. Both were for heavy duty truck applications with the slant 6 and quite rare.

I suspect the mentioned bell for the flathead 6/ V8 is a pretty rare critter as well.
Rare in Mopar speak usually represents many $$$$$$$.
Gene

Well it isn't rare, they were on Dodge smallblock pickups through 1968. While looking this up I came across another bellhousing from a car, not the same casting as mine but you can see it here: http://www.ebay.com/itm/57-DODGE-CORONET...38c&vxp=mtr

Look at the lower attached picture for the flathead 6 mounting pattern. It shares the top bolt hole with the A/LA bellhousing.

Here is an excerpt from Sweptline.com:
"all truck small block bell housings are the
same castiron bell mounted to the crossmember
from at least 62 to 68 (used behind all truck
small blocks, slant six and the old flat head
six- across the line from the flat fender Powerwagons
D and W 100 200 pickups and Townwagons/panels). This truck bell was used in front
of all the manual truck transmissions offered
in those years (3speeds and 4 speeds
as well as some 5speeds).
I assume this bell is stock since it has a
np420 mounted to it (a 420 will not mount
to any car bells in those years). And from
what I can tell from my 66 parts book- and background- nothing
changes for the truck bell in those years."

The 340 pictured has the same bellhousing as was in my '64 and it has the wraparound BH which has the flathead 6 mounting holes in the front flange, ahead of the flywheel.