Trackson d4 question

Tractor is a 1952 model with D315 engine.
SFG is a new one on me but I suspect it has to do with special gearing in the transmission.

I've never seen SFG stamped on any Cat, but there's always something new to catch you out.

"SP" after the S/N indicates "Special Parts" that are installed on the assembly line. These were usually options or attachments such as lighting options, batteries and heavy duty generators, optional transmissions, and a range of other items too long to list.

The "SP" designation was discontinued in Dec 1946 for all factory-fitted options and attachments, except for special transmission and final drive gearing.
However, Caterpillar warned that the absence of "SP" as a S/N suffix after Dec 1946 was no indication that the tractor was a standard tractor, and it still could have "special parts" fitted.

"SPC-G" stamped on the upper right rear face of the steering clutch housing, on D8's, D7's and D6's of the 1940's and early 1950's, indicated "special low or high speed transmission gears".
This meant that a standard transmission could have optional gear groups installed, but there was no other markings to indicate such.
The transmissions with these gears fitted did not have any special part numbers or other markings to indicate the gear speed alterations, thus the markings on the steering clutch case were to warn repairers about them.

(SPC-G info - Service Magazine dated Feb 19, 1940).

The HT4 had no fifth gear and 2 reverses. SFG = Special ? Gear

Regards,
Dozer 2442

thanks guys! I have not gone to look at it yet just seen photos but appears to be in decent condition they say the clutch needs adjustment and pony motor needs work so who knows what that really means. I looked at it again and I think it is actually SPG the p is overlapping the G and looked like a F

I seem to recall sometime in the late 1940's, Cat went over to using just "SPG", instead of "SPC-G" for special transmission/final drive gears - but I can't find any specific advice on the change, because I'm missing quite a number of Service Magazine issues from the late 1940's.
I would think that Dozer2442 is correct, the SPG refers to the transmission gear differences between the HT4 tractors and the standard D4's.

Hi Team,
great to see you back OZ.
here are copies of said SM's. Feb 19 1940 and Feb 20 1941.
So far have not found anything later except for an article on Special group Number Plates for D6,D7,D8, No6, HT4 and 583 in a Service Bulletin - Track Type Tractors - Nov 18 1955 now added to this list.
Cheers,
Eddie B.

Thanks Guys here are a few photos. What do you think? I know it is tough to judge until I go look at it in person but looks to be in decent shape. Is the clutch adjustment on this HTD4 done in the same manner as my 5UD2?

I particularly like the exhaust cover 😆

for some reason I can not open those pictures ...