Trans E is E4OD, four speed automatic Overdrive. According to the owners manual on the 1990 F250 I bought for parts, 39 axle is a 6250 lb capacity Ford 10.25" 3.55 ratio open rear end. The parts truck has a C9 code axle for probably the same capacity, but limited slip. The tag on the axle says 3L55. If you need an owners manual, this one is going to be available.