Quick question.

I know the V8 heads inside out.

But what exactly changed when the 173/202 head went from casting numbers 2811929 (H) and 2811930 (L) to 9937262 (H) and whatever the 2850cc head was? These are the HX-HZ, late LX and UC plus VB heads.

I remember vaguely it was just an extra threaded hole for the head temperature sensor maybe? The rest was identical to the HQ-HJ castings?

Thanks Terry. I was at a place yesterday with a dozen or so red heads, and know someone looking for a 929 head. I'd told him the pollution 2850 head will do exactly the same job but just wanted to confirm.

I think that head is the 2 i have seen with a casting that is Blue head casting like in being having flat faced surface, as when you look at the casting numbers, look along that top edge front to the back on top of the intake and exhause manifold just below the tappet cover, every red head i have seen is always cast curved over like. but this type is just flat, but where the numbers are it's just curved over like normal, but it's more to the frount and rear that differ being flat like, i took a photo of such but the numbers could not be seen. but i know the numbers started with 99 .

I seen it first in a very late HZ 3.3L casting on the block 1 tonne at the wreckers and the next one in a hotrod that a ex car dealer ownes. such sticks out like dogs balls. i did not note the threaded hole tho, but i will look on sunday if it's down at the car show.