Reply to Old Magnet:
No, there were major changes to the whole set up when they went from small to large track truck bearing arrangement.
R4Pat - The final drive design of the D4 was changed almost totally in early 1945, at D4 S/N 2T8270. This new design, with an easily distinguished, large outer hub bearing, involved virtually all new parts, as compared to the earlier final drive design as fitted to the D4 9G, 7J and earlier 2T series tractors, up to 2T8269.
The only part I can find common, is the inner spocket taper roller bearing. Here's the two pages from the parts book, you can do your own comparison .. 😊
D4 7J series final drive ..
http://img24.imageshack.us/img24/6505/d47jfinaltg2.jpg
D4 late 2T/5T series final drive ..
http://img24.imageshack.us/img24/196/d45tfinalhu3.jpg