I pretty sure I have one. Mike

I will check this weekend. My number is 309 737 4752. Mike

Hi Neil,
sorry, I do not have that sort of info to hand. Need an NPR or such to follow the supercessions thru.
By some Parts Books I have it looks like the pre-combustion chambers are the main differences--there maybe others. Studs appear to be the same for both P/No heads.
From memory early chambers do not have the spline to remove them--need special Cat Tool Group that grips the chamber somehow by multiple pieces.

My Valve Seat Specs. Chart shows both Part Number Heads have the same valve seat specifications at least.

All Head Part No's for D3400 engines shown on my chart are :- 7B0596, 7B0607, and 4B3073--all have the same seat specs. as at 02-1958.
I stand to be corrected.
Hope this helps.
Cheers,
Eddie B.

edb is correct, the main differences from early D3400 heads to the late ones were in the precom chamber areas. The earlier ones had a different internal precom chamber design and also utilized small set screws in the side of the head to help retain them, whereas the later heads did not have these. It doesn't matter which style you have, everything will interchange just fine. Injectors, studs, valves and guides, and whatnot will fit in either one.

Too bad, you didn't find out sooner, I could have picked that up in Walworth, thrown that in my Subaru to get it as far as Olean, NY on Feb 26th.