Can anyone narrow down the year of my D2 serial number 3j101.? The book I have says from '39 to '47. Thanks!

The Cat SNID book says they started production in 1938 so as low a SN as you have it could have came out that year or 1939 I,d guess.I did notice you had a question mark after your SN posted so was-is there more numbers or not? If there were more numbers they would have to be present to know the exact year made.

3J101 would be a 1938 and I dont read it like SJ but if if it does have another number after it it would be 1947 and would be easy to tell by the ezaust on the ponymotor

3J101 is all there is. thanks for the info. I bought it a year ago ,but just beginning to work on it now. previous owner said it just needed the starting pinion lever freed up and it would be good to go.Well, after steam cleaning it,removing the pony motor,main motor,got it out and freed up.also replaced the clutch since it was accessable. after cleaning several layers of dirt and grime off with the steam cleaner,found several aplications of jb weld on the front idler bearing blocks.now the tracks are off,front idlers taken apart and using the very helpful supplier list above to locate some leads on the bearings.Great site. Thanks