Few questions on what engine was used in what serial number crawlers. Let me know if I am correct on my assumptions below:

D2 5j & 3j is D3400 4 cylinder
D2 5u & 4u is D311 4 cylinder
D4 7u & 6u is D315 4 cylinder

What does a D318 fit and how many cylinders does it have? I think it was used in a D6 and it is a 6cylinder?

Yes you are right on the D2 & D4 engines & yes the D318 is used in the D6 8U & 9U tractors & they are a 6 cyl. version of the D315 pretty much.

mkreh23

I believe you are correct RE the D2 and D4 and inpart on the 318, It was used in the 8U and 9U D6 as well as a long list of equipment such as generators and stationary engines and yes was a 6 cylinder, before the 318 the D6 used a 3 cylinder similar to the Diesel 35,40 and RD6

The early D6 with the 6 cyl. engine after the 3 cyl. was called a D4600 & was a 4 1/4" bore same as the 4 cyl. D4400 in the earlier D4s like the 7Js & 5Ts etc.

The D318 was indeed used in the U series D6 tractors, the No6 shovel and 977 20A loader, the D4 of the same era used the D315 as did the 955 12A shovel. But the earlier D6, 4R and 5R series used the 4600, 6 cylinder 4.25" bore engine while the D4, 4G, 7J, 2T and 5T series machines used the 4400, a 4 cylinder version of the D6 engine.
There was therfore another engine between the 3 cylinder D6 and the D318 engined version.

Missed one:)
The D4600 in the D6 4R & 5R series came between the three cylinder D6600 and the D318