I came this across this at a junk yard over a year ago. I'm 90% sure the tag said 30a or 39a. They wanted $1500 for the engine and clutch, missing the inj. pump and water pump. The price seems kind of high considering nothing
was covered. I did buy the pony for $200 which bolted right up to the
d4-7j7652 . The 30a pony had a eiserman mag and water flange going into the back of the head. The 30a engine sure looked like the 4400 with the
nozzle return lines. I was under the impression the 30a came after the 7u
At any rate I jumped the gun on my 7j by obtaining a pony for it then finding
out the block is cracked behind the inj. pump and the head is cracked between all the nozzle holder bores. I'm still toying with the idea of stitching
the block and replacing the head. The engine turns over fine, exhaust ports
are clean, and no water at all in the oil.
Can anyone shed some light on the 30a ? (am I looking at some years ago
repower job)

The D4C -39A (narrow gage) and the D4C - 40A (wide gage) came after the 6u/7u series and used the D330 engine.

The D330 used an entirely different pony motor (side mount) rather than the flat horizontal flywheel housing mount so yes, you are probably looking at an old engine transplant. Could even be a D4400, right for your 7J.

I don,t know what you have there as the 30A D4 was made in Au in 1958 & it wouldn,t have return lines even if it was a D315 or the D330. If the pony fit yours it wouldn,t be a D330 engine as they had the pony on the side rather than across the back like your 7J.

Thanks OM and SJ , Looks like I''ll be making a expedition to the junk yard.