J-Head Cores (915 casting number)

There were many 1971-73 J heads that were 1.88 int valve ...and they were in vans. A ton. 1970 J heads were 2.02.
It's odd that they're missing some digits because that's indicative of a later 78 or 9 head but it does not have those air injection for smog follow the exhaust ports and they clearly have the J and the 360, -F etc..