guy says it's LT4 heads.

 

Aren't they the '561' 96-7 LT1 heads?

 

It is a LT1 head. The LT4 has larger intake ports and 2.00/1.55 valves and the LT1 has 1.94/1.50 valves. If you have a LT1 intake compare it to the heads and you will see the dowel pins on the gasket are in a diff. location on the LT4 heads, they are closer to the outside of the head about 1 inch or so. Hope this helps. Someone may know the LT4 casting #'s but I do not.

NightTrain66

 

12555690 is the casting #

 

Many of the LT4 heads I've seen actually have "LT4" cast into the top of one of the port runners.

The guy is trying to sell you a 96+ LT1 head. Another easy way to tell the difference is that there is a rocker stud boss that protrudes into the port on LT4's, along with a ridge near the shortside between the two adjacent intake ports where the headbolt hole is, where all LT1 iterations have neither.

 

Oh, you talking 'bout those 'speed bumps', Phil?

 

No, I think restrictions hanging in the ports are what the LS1 guys love to claim are there to induce swirl! Swirl Swirl Swirl! Swirl my ***.