Power Unit

Flywheel housing, oil pan and oil pump are not the same as the 7U. Governor arrangement and rack settings will also be different. I'd have to do more digging but I don't believe the front timing gear cover is the same either.
On further check the timing cover is the same.
If your tractor doesn't have the engine balancer the early belly pan will not fit the later engine with balancer. Would require the later belly pan.

Thanks for the info Old Magnet you are always on top of things. Could you possibly give me an idea of what year it was built. The number on the tag is 9S11838. I guess I can use the cutch housing for measurements to cut the hole for starter in the 7u housing. If anyone needs a pan, front support, clutch housing for a D315 power unit let me know as I don't need them and I have to see good parts go to the scrap yard.

My listing doesn't go to that high a s/n so I'm guessing 1957, 58, or 59.
Use these dimensions to bore your flywheel housing, not sure if the Industrial Housing is the same. I was fooled by a D318 Industrial Housing not being the same as a D6.

Bell housing is different power unit to d4 dozer. A friend of mine is doing the same swap.
Chuck C

Maybe I wasn't clear. The housings are obviously different but it's the starter hole location dimensions that I was referring to.

Set up 2 rows of letters and numbers as so

N U M E R A L C O D
0 1 2 3 4 5 6 7 8 9

I can't get the spacing just right but you get the idea. The main pieces, the engine block, oil pan flywheel housing and possibly others will have a 5 or 6 digit letter code. That will transfer to the number chart. This is the casting date, and will be within a few months of later assembly. May have to wire brush or clean heavily to see. Still works today as far as I know.

Good luck,