Just a wild guess, but is it possible that the same core support might have been used on heavy duty trucks with a bigger radiator- - - - -one that might have needed the wider-spaced holes for a different type of support? I seem to remember there being an optional radiator for heavy duty applications like dump trucks, etc.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!