[Coley]

Originally Posted by mechanicalman

As GRX pointed out, your heads do not have pushrod guides just round holes where the pushrods go through the heads. Look at your 72 rockers they are flat where they rub the valve stems and the 72 heads have rectangular shaped guides in the heads to guide the pushrods unlike the heads you just obtained. You have to have one or the other if not the rockers will slip off the valves.

Look at the picture I posted and see the dimples on the rockers on each side of the valve stems, that's the only thing in this case keeping the rocker arms from slipping off the side of the valve stems. Here is another picture:

Great info guys.....I checked the rockers on the spare heads I have in the basement and they do NOT have that stamped recess....interesting.
I will do some more checking on this prior to any installation to ensure that there is no 'slip off'.
(I might also see what style is on the truck now with the older heads?)

All Good
Coley