56 ADs will work with 53-56 grill. 53-55 do not work with 56 grill. Could be dealers/parts houses stopped carrying the earlier ones for replacements once the 56 came out.
The difference is obvious once you see them both:
53-55 http://blueovaltruckparts.com/catalo...oducts_id=6664
56 http://blueovaltruckparts.com/catalo...ducts_id=14204
The parking light housings are also (but more subtle) different shape.

 

The 56 headlights are frenched back into the the grill to reduce the bugeyed look across the front. thus the air deflectors had to have a dimple to be able to mount the headlights back further..

Hoping to find a decent 56 grill for mine too..

Sam

 

That was the case with my truck. My uncle was in a wreak long time ago when my Grandpa owned the truck. A car ran a stop sign and hit him on the left front. When I rebuilt the truck in 1997 we noticed that the left front air deflector was a '56 model. The hood I found out later was a '56 hood (the difference is that '56 hoods have the 2 bolt heads at the back of the hood near the cowl). My grillw was a ****e color not the ivory color of a '54. All this was done because it happened after 1956 and they used what they had at the dealer body shop.

 

Thanks for the info, it clears it up very nicely AXracer.

 

Also, the '53 are slightly different than the '54 and '55. The '54 and '55 trucks have 2 rods that cross from side to side, they form an 'X' in front of the radiator. I think they are used to make the front end more stable and solid. They have 2 little arcs at the sides of the deflectors to allow the rods to pass by. The '53's did not have these. The '54-'55 will fit the '53 but not vice versa.

 

Hi , I was just wondering because abe had mentioned that the 56 hood was different than the previous three years, the difference being the bolts at the cowl. I have three hoods all from 56 models and one from a 53 model which is the only one that has the stove head type bolts up close to the wind shield. I'm not trying to provoct an argument but was wondering if there may just be a difference between the USA models as compared to the Canadian models??
John

 

The 56 headlights sit in a little, a frenched look; not like the bug eyed 53-55 look.
This is why the air deflectors have a bump in them, for the clearance.

You can modify your old ones, and since they hardly are noticeable, they can be a good part to practice on. I saw one guy who just cut a circle about 6 inches and screwed on a modified small coffee can.

No, it wasn't me.

Paul

PS: I had to darn nearly give away my 54 grill, complete with new whiskers and parking lights about 5 years ago. Guess I should have thrown it on the junk parts pile with everything else!
I may have the lower valance for a 54 if necessary.

Paul

 

Also, you can modify the parking light housings with some careful trimming. I did that once to make (I believe) the 55s fit a 56.
I can't recall which ones are smaller/larger, but it's not much. I've seen small ones built up with a careful application of a U shaped rubber gasket around the edges.

Paul