I have several coolant overflow tanks of 2 variations. Just wondering what the fitment might be. The tanks are virtually the same but the top is slightly narrower on 2 of them. thanks!!!

I've had a lot of Dodge trucks in the past. To tell the truth, I've never noticed (or at least paid attention to) the difference! Wonder if the small ones were from lighter duty applications, like a slant 6 stick? Looks like not all of them have the hose attachment on the same end either.
Here I thought they were all the same, but maybe all mine were....Gene

You could be right. I cannot remember what they came off, I've had them for about 15 years or so..

There is a distinct difference between 79 and 78's - size and hose exits etc... But yes even within years there are a few different sizes - no idea how they determined which one for which. Lil Red's in 79 had different sizes - trust me I know I reproduced the one I had and there have been fitment issues...

mounting....if when mounted the hose end comes off of the drivers side then it is 78 and earlier
if on passenger side hose outlet, then it is 79 or 80...

back to our regularly scheduled programming....

I never paid much attention to it either but I thought I read somewhere there is a difference depending on if the hood release is behind the grille or in the cab.
My parts book says 79/80 just has one part number for all applications.