"the 77-80 heads w/ 61031 casting are a slight improvement over 61030, plus it has the extra coolant temp ports cast over (one less crack/leak point)."
They are both open chamber heads so I would say they are interchangeable.
"Stay the Trail," "Tread Lightly," and "Leave No Trace" ethics
Rising Sun Bio
2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering,
soon to lose the Sanden OBA
to go back to factory emissions
1FZ-FE factory lockers + Safari Turbo
, CDL switch, cup holder, AATLAS1X leather, heated seats and JDM switches
Limited TRD 2UZ-FE SOLD