['68OrangeSunshine]

Today radiator manufacturers don't make the OEM style L6 width radiator. They have standardized on the wider V8 type, and for automatic transmissions.
Don't panic. The extra width is welcome as it means more cooling surface. [You live in the Desert, right?] All you need to do is relocate the passenger side upper and lower radiator brackets from the L6 to the V8 position.
The brackets on the drivers side stay the same. The passenger side ones move to the truck right, somewhat, about 2-1/2''.
You may need a longer lower radiator hose. On my 292 -- modified for V8 radiator -- I use Gates p/n 20489 for the lower hose. Upper hose is unchanged.