blade interchange among D4?

Hi Nick,
The general answer is yes but there are some hurdles.
Tractors 7J7319 to 5T6473 did not come with the tapping strips provided for mounting to the track roller frames. These would be installed by removing the front three track rollers and once bolted up need to be welded in place. I don't recall at the moment why the cut off going back beyond 7J7319 but I suspect they are the earlier style track frames.
Also if you want to run the #44 hydraulic package you would need the early style pump drive for the D4400 engine.

Now that I'm awake and had my coffee I need to amend the 7J7319 to 5T6473 info. This pertains to modifying the front guard only. The one that wraps around the back of the idler. This needs to be altered to a two piece version like later units.
The blade mounting can be done on all the D4 models.

One other thing make sure your 7J is a wide machine 7J????W, In the U ser. the 6U was narrow 7U wide in the G,J,2T&5T reg ser. no. was narrow or standard and the wide had a W stamped at end of ser.no.

You are not limited to mounting blades on wide gauge tractors. They were available for both 44in and 60in gauge.

OM thats smart oif you to figure that out on your own. But he says the blade is from 7U thats means its already wide, would take lots of work to adapt to standard gauge

Willie,
If your so smart then how about coming up with the answer as to why the blade mounting cut off at serial # 7J7319 back.

The wide vs narrow application is just for general information as I'm sure others are monitoring this post.

Im not smart at all I was just answering the mans question about HIS 4S-7U dozer blade fitting HIS 7J. And what ever mounting hole in any 4G,7J,2T&5T they would be for Le Tour, Kay Baldwin, Lap C. or B.E. unless put there in later yrs would not be for the Cat 4S dozer because Cat did not make a dozer till after the war. Prewar Cat depended soley on John Deere Kilifer for tillage equip. and Le T for construction equip. they would be for Le Tour, Kay Baldwin, Lap C. or B.E.
My guess is that Ser. no. came from reprint parts book yrs later where Cat made replacment trac frames for all the big hubs for mounting their dozer but i forget when the hub changed

I have a slightly different take. It appears that the bolting pattern (holes) were established long before Cat had a blade as you say but tractors 7J7319 to 5T6472 did not have the tapping strips in place and had to be added. I'm thinking that tractors prior to that did not have the mounting holes drilled. I still can't explain whether or not there is an interference problem with mounting the tapping strips on earlier tractors as I know I have seen older units with Cat blade mounted. What I don't know is what/if any modifications had to be made to get it mounted.

Can anybody comment on these mounting requirements?

Both 6G210w and 6G264w have the holes drilled . leroy