Jim.  In the link below, MarkMontereyBay is offering a set of exhaust manifolds for sale. 
- The passenger side exhaust manifold unit is the later style that connects a heat tube to the carburetor automatic choke rather than using a heat tube inside the intake manifold as Ford used in '57. This exhaust manifold will work on your '56 'Bird and is more efficient than the '55 Merc unit you have.
- The driver's side unit, I believe, is the EDB casting ID unit John (Hoosier Hurricane) identified in this link as coming off of a later model '59 312 Mercury that is identical in configuration to what was used on '56 and '57 'Birds.

http://forums.y-blocksforever.com/FindPost141293.aspx

I've included two pictures Mark posted of the driver's side exhaust manifold.  I identify this as fitting the '55-'57 'Birds because the rear exhaust manifold bolt, the one closest to the firewall, is accessible before the manifold turns down. On the passenger car exhaust manifolds, the rear bolt is only accessible beyond where the manifold turns down.






Hope this helps!    


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Sandbarfarm31.  My understanding is that the '55 and '56 Mercs with automatic AND standard 3 speed or 3 speed w/ overdrive transmissions use the same driveshaft yoke.  My experience is that having both of these '50s transmission types using the same driveshaft yoke is an unusual thing. The transmission yoke needed has 16 spline, was a Spicer application, and I'm told has been out of production for a l-o-n-g time.

Consider trying to obtain the original driveshaft for your transmission from the fellow you got the engine and transmission from.  No, it is the wrong length and tube diameter for the '56 'Bird, but you need the transmission yoke.

The '56 'Bird has a Dana 44 rear end in it that is different from what was used in the '55 Merc as I recall..  I'd look for a '56 'Bird auto transmission driveshaft. I think the length will be correct for your '55 Merc automatic.  Perhaps the Merc 16 spline yoke can be used with the 'Bird drivshaft.  Overall length of the driveshaft assembly is information that I don't have.

John (Hoosier Hurricane) may know for sure. 

The '56 'Bird 312 engine with the 3 speed w/overdrive transmission would be another source for the correct driveshaft yoke with the 16 spline Spicer yoke.  The transmission in the '56 3 speed w/ overdrive transmission was a Borg Warner T-85 w/ an R-11 overdrive unit.

Hope this helps. 


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Driveshafts can be made and are not that expensive, so no problem there.


Lawrenceville, GA

I am just trying to get a running car. No pure restoration. I am wondering if finding a driveshaft is going to be another challenge?

If you use the T-Bird damper you will need to use a T-Bird timing pointer.

Jim:
I suggest you get a catalog from one or more T-Bird vendors.  They have nice illustrations showing their parts and corresponding pieces.  Also you can get an idea of available reproductions and prices.

John - "The Hoosier Hurricane"

Dipsticks are reproduced.

A pickup tube was available on eBay fairly recently but it was damaged / repaired / modified.  Here is the link.  It's not currently listed but you can contact the seller to see if it is available.
https://www.ebay.com/itm/1955-1956-1957-Ford-Thunderbird-292-312-Y-Block-oil-sump-pick-up/332715188296?hash=item4d775ee048%3Ag%3AzQsAAOSwRWRbQ-PK&_pgn=1&_sacat=0&_nkw=y+block+oil&_from=R40&rt=nc

The pickup tube may be cheaper to make since it is a 'bird only part and will probably have the 'bird only price if you find a good one.  You could do that by cutting up other pickup tubes and welding pieces together to fit.


Lawrenceville, GA

Wow Charlie this is exactly what I need! A concise list! I believe a nice fella is providing me a T bird oil pan ( will still need an oil pick up and a dip stick) and a front cover with motor mount. This is a great forum and I sure appreciate the help!!

Sandbarfarm31.  Below is a composite list of original 'Bird engine parts to re-purpose the '55 Merc engine you've acquired for use in your '56 'Bird.

NOTE: 
- 55 Merc passenger car engine is 6 volt starter, ignition coil, and generator
- some have suggested use of an alternator instead of a generator to eliminate need for the 'Bird components
- some have suggested use of a passenger car crankshaft damper to eliminate use of the 'Bird water pump spacer

Needed Parts:
- 'Bird or truck front timing chain cover (to accommodate use of a front engine mount)
- 'Bird water pump spacer for the timing chain cover 
- 'Bird only crankshaft vibration damper (learn info about used 'Bird dampers before going shopping)
- 'Bird timing pointer (Needed for 'bird damper.  Forgot to list this!  Thanks, Sandbird)
- 'Bird engine dipstick and dipstick tube
- 'Bird only rear sump oil pan and oil pump pickup assembly
- 12v starter and ignition coil
- 'Bird 12v generator OR modify a 12V passenger car generator using 'Bird front pulley and an alternate wiring connection on rear plate
- 'Bird generator bracketry
- 'Bird only thermostat housing
- 'Bird driver's side exhaust manifold  NOTE: indication that '59 & '60 Mercurys with the 312 have an exhaust manifold with different casting # that will fit 'Bird application!  Casting number is an EDB prefix
- 'Bird motor mounts (side engine mounts and stabilizer rods plus front motor mounting system assembly and components)
- 'Bird OR later passenger car or truck valley pan with rear opening for crankcase ventilation tube OR use of PVC set-up
- 'Bird or later passenger car valley pan draft tube
- a set of standard y-block rocker arm covers to replace the '55 Merc embossed lettering ones

Eventually may want to obtain . . .
- late '57 up y-block spin-on oil filter adapter
- '57 or up passenger car ignition distributor to replace the '55 Loadomatic distributor
- 'Bird air cleaner

Hope this helps, Jim!    


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

John
I’d be interested in the rusty Tbird oil pan as I’m trying to keep it a budget build. Email me at: sandbarfarm@hotmail.com
Charlie has very graciously sent some possible parts provider as well. Thanks much, Jim