D2 Serial Number?

hello bmg504570 and welcome ,your d2 5J3340SP is a 1940 built machine ,
sp is for special parts ,quote sp means special parts used to replace standard parts ,transmission gears ,over sized idlers ,electric starter instead of starting engine ,and other parts that need special attention on assembly line .bruce oz

bruce oz Wow Thank-You for your quick reply! This D2 has a belt pulley on the back, maybe that was what the SP was for?

hello bruce ,the belt pulley want be the sp part ,i should have put that in the first post ,not any add on accessories like pulleys ,cabin,lights, crankcase guards ,mufflers,

most like to be trans gear changes ,higher ratios ,post some pic up if you have any ,thank you ,we like pic 😄 ,bruce oz

Welcome Bruce:
Your D2 in the year which it was made actually came in two sizes. The 5J, which is the wide gauge, and the 3J which is the narrow gauge. Later Cat made the 4U model, which is basically the same as the 3J model except that it had more horsepower. The last of the D2 models was the 5U. A wide gauge model with a direct electric start feature.
Enjoy your new toy.......
Feel free to ask questions as there are alot of knowedgable people who can answer many of your questions. 😊

Mike

Narrow gauge D2 was 40" from center of sprocket to center of other sprocket, and these were the 3J and 4U models.

Wide gauge were 50" and were designated the 5J and 5U.

Both wide and narrow gauge tractors of each series were produced concurrently with more wide than narrow produced. The diffence in production became even more pronounced in the later series with about 2.5 times as many 5U's produced as 4U's

Each series of tractors were continually improved through the years they were manufactured, but the series changed in late 1947 from the J series using the D3400 3.75" bore engine to the U series using the D311 4" bore engine. There was also a major design improvement midway through the 1950's for both the U series D2's which allowed clutch removal without pulling the engine and resulted in a slightly longer tractor. I believe there was another hp increase about that time as well.

Optional direct electric start was available on both J and U series, but rope start pony motor was standard equipment with an optional electric pony motor starter available