The GMC CCKW

I can cure that with new ones. Also have a limited supply of the Bakelite carburetor Insulators for them. Be cafeful when removing them, if they are not slid up the studs evenly, you will shed a tear. I start them with a knife, as screwdriver may break them. Use plenty of WD-40, the spacers are rare and costly.

Intakes are NOS WWII In Cosmoline. I may have an NOS AFKW intake stored away also.

Exhausts are both NOS GI Surplus and the Last of the NOS Civilian 270 Manifolds purchased thru my local GM dealer in the late 80s (I stocked up many years ago as these are scarce)
These are no longer available thru General Motors System. I can supply all the studs and gaskets with these.

Intake and Ex Mainfolds when purchased together include spare studs, new brass nuts and all gaskets necessary to install manifold to head and attach to Ex pipe.
I may have used Ex manifolds from the M 135/M-211 with the 302 engine, these are the same as the 270, and because they are used, may be warped. They not only warp at the gasket mating surface, the intake may warp vertically, making it impossible to install the pilot rings. Without pilot rings your engine will have a vacuum leak that will prevent smooth operation and idle.
NOTE:
Only the exhaust manifold from the Hydramatic Shift M-211/M-135 will fit, the Intake does not fit a 270. Used Exhaust manifold is $150.00 plus shipping. The studs that attach the late 302 manifold to the intake are too short and will have to be changed, these may twist off during removal.

ALWAYS LEAVE THE CONTROL VALVE ON THE EXHAUST IN THE SUMMER POSITION YEAR ROUND, IT WILL HELP ELIMINATE THE HOT SPOT AT THE MIDDLE OF THE EXHAUST WHICH CONTRIBUTES TO THE CRACK THAT DEVELOPES AT THE CENTER. This will slow down the warm up of the intake by a minute or two, but will add years to your manifold.

The above little tidbit had proven itself thru 45 years of observation of this practice which was first brought to my attention by my good Instructors at the Wheeled Vehicle Mechanics School back in 1960.

There are civy (early) 270 intake manifolds out there, but all I have seen do not have the big threaded vacume port for the brake check valve. You CANNOT have them drilled out. You will break thru the casting into the exhaust carb heat area.

The M135/211 intake manifold is the same as the 4 bolt carb'ed civy 302 manifold.

The 50's 270 intake manifold is different in that the head and ports are bigger in diameter.

The 50s 270 intakes are in essance 302 intake manifolds, they will never fit a WWII era 270 Cylinder Head as the ports use the larger 302 Pilot Rings. All of my NOS 270 intakes are the Genuine WWII with all the holes, and are dripping with Cosmoline. All WWII CCKWs from the CCKWX on had the large plug in the rear portion of the intake manifold, it started as part number GM 2091334, and the hole was used on the Pre Hydrovac CCKWs for the Check Valve for the early Brake Power Cylinder. Any of the Intake manifolds listed in the SNL for the various CCKW types interchange, whether the supercede each other or not. The CCKWX manifolds did not have the plugs used for the Cold Starting Hand Primer system that injected atomized fuel into the manifold, but later CCKW Intake manifolds did. You can easily tell if your intake is the later CCKW as it will have a small (1/4" pipe plug) at either end facing the Driver's fender.
Joel

The 50's engines have the bigger ports as I stated and will not work.

A 50's 270 manifold uses a single barrel carb and the 302 uses a double barrel carb held down by either 3 bolts (Holley) or 4 bolts (Stromberg or mil 302)