70 Chevelle BB Radiator Bottom Extension Bracket ?

[XXXGoldL34M20]

I know the complete story of the Big Block upper plate radiator cover which had the welded on tab on the drivers side to simply accommodate the support of the 4 core radiator or an Air Conditioned ordered big block car.

But what is the story on the bottom welded extension bracket as this argument comes up many times for me at cruises among BB Chevelle guys?
Only 4 cores came with these?
Air cars had them as well?
Where they all welded on all the LS6 rad supports as standard?

[SS427]

Only on heavy duty cooling (4 core and A/C cars) regardless of engine. Many LS6 cars had the three core and therefor no welded extension bracket.

[XXXGoldL34M20]

Thanks Rick,
So it seems as though it is the exact same story as the top welded extension on the cover plate.

[Mr70]

Yes,to accommodate the larger D/S HD 4 core tank,as the passenger side BB 3 core already had it.

4:10 equipped LS-6's received the HD radiator as std. equipment.

During resto,some 1970 SS Chevelle 3 core car owners have erroneously bought the Heavy Duty 4 core welded top plate,thinking their car originally came with it w/o looking @ the build sheet or getting on their knees and looking down there to realize they made a mistake as their car is holding it's original 3 core support.