I bought a 55 that seems to have come off the Air Force base in Victorville CA. Painted crudely Desert Camo Tan.

It has a Dually with 6 lug wheels typical of an F350 and higher even though it was sold to me with a Data Plate as an F250. It does not have a bed, and appears to have been a flatbed.

It's had enough futzing that there's no way to be sure it's the original Data Plate. It has a 55 grill, and the front doghouse appears original to the truck. It however has a 56 hood with rivits both sides of the rear crown, so no way to identify the series my truck was thru the hood emblems.

I thought it had a 239 Y, but I'm begining to wonder if it has a 256 cause it appears to have an original intact 4 Bbl. manifold, which was original to the 256 and larger 55 engines. I suppose someone may have replaced the manifold but it looks like it's never been disturbed. If someone hadn't scavenged the Carb off before I got it, I would be able to clarify whether the manifold was original.

I have a 54 / 55 Shop Manual and the original Dealer Truck Handbook that identifies optional equipment, and a 239 wasn't Spec'd with a 4 bbl. A 256 was Avail. Spec'd in an F600, but my front fender wheelwell openings are not the Big Truck large wheelwell openings.

Now this is all just speculation and hypothesis from the sketchy information I have Avail. It was untitled. I do however know that it is not uncommon for Gov. Contracts to specify changes to equipment for fleet vehicles outside original equipment Spec's.

1) Can anyone help me with casting numbers and locations that will help me clarify this puzzle, Is the block a 239 or 256, is the manifold original to the block?

2) Apparently 55 279's and higher were exactly the same and fully interchangable. The Shop Manual does not indicate the difference between the 239 EBV / EBW, and the 256 EBZ. Were the latter also the same blocks, water passages to heads?

3) The whole question is important to me because I have had a Pr. of heads rebuilt and am trying to clarify which gasket set I need. Are 239 and 256 Y-Head Gaskets interchangable?

I've located a Pr. of original steel 256 Head Gaskets if they will interchange. Thx. for any help this post rustles up. David

 

look back by dist,a 239 will have ebv cast on block.a 256 will have eby.

 

All 239/256 car engines are fully interchangable with parts. The head surface mating patterns and distributor are unique.

Trucks are a different animal. They started out with a car type engine and the peanut valve heads but quickly changed to the later design.

Ive never seen a Cleveland built EBV or a truck 256 EBY with the ID by the distributor, they are all on the block above the oil filter. Not to say some very early Dearborn built 239's werent used; I just havent seen one.
BTW, in late 55 and 56 the EBY casting was also used in the F600 272's.

The Clevelands all used the larger 1.78 valves and everything interchanged with the 272 and 292 thru 1956. In 57 the big port heads came along as well as a new design distributor, intakes and carbs. Performance builders get real fussy about which interchanges are good, for street trucks it doesnt matter IMO.