D4 2T radiator core part number

2A1164 is the radiator core for a 7J6436 to 7J7318.
4A0149 is the radiator core for 7J7319 to 7J9999, 2T1 to 2T9999 and 5T1-up.
Radiator assemblies often get swapped, make sure you have the right one.

Thanks Magnet!

I looked up those two part numbers and it appears that they are interchangeable.

Yes, I looked at one of my aftermarket parts manuals and it shows 2A1164 covering 7J, 2T, 5T models.

In many cases the low part numbers in the 4a series are WWII redesigns to save critical materials. Such as brass, copper, aluminum. Thus the 4a parts can be steel, or cast iron. In most cases after war parts reverted to original numbers and material, according to npr. Thus the 4a radiator core could well have been steel rather than copper.
An example of change in material, is the drive disc in my sixty with the diesel conversion, the drive disc on planetary was originally aluminum, this one had a cast iron one with a 4a number. Another planetary has an aluminum one, with a casting date in the late forties.