Hi Daron,
Changes in those early 50's models were pretty subtle.
The big change was in 55 when they dropped the "straight eight".

 
A Caterpillar Diesel tractor using a winch to haul logs into a sawmill.

These old photo's are great, and would make a really good calendar, thanks to Seyser for sharing them. I think this last photo might be a D50 or RD7, pretty sure its not a D6, but I'm usually wrong. LOL

This is easy to see only a 4 cylinder engine. So you must have gotten this one right Mike.

The 3 cylinder diesels all had the fuel tank in front of operator. Then the 4 and 5 r series D6 had the air cleaner in front right of engine. I believe the Y shaped dash as this picture has was the same basic shape on all 4 and 6 cylinder diesels from the 1930's to late 1950's, maybe a bit longer.

Dose Cat have archives of old pictures? My uncle had several of grandpa's D 35 that he claimed Cat had taken. Probably in the summer of 35 as one was pulling a Case sidehill combine. Grandpa got a better deal on the D35 by letting the dealer bring people around to test drive it. As it was one of the first 2 diesel Cat 35's they got from the factory. The story was Cat took pictures they might use in advertising, but gave grandpa copies. I have asked cousins if they have seen the pictures in modern times, but nobody admits to seeing them or knowing about them.

Old wrote:

1951 Pontiac car in the picture.
 

OMG! of course! my grandma had a 50 or 51 Star chief!  That one in the old pic looks horrible! lol  When I was about 5 or 6 I rode to the market with her one time and she would power brake it at the stop sign, spun the tires in the gravel, I laughed my #$% off, it was so funny!

 

   
 

steve_s wrote:

Just out of curiosity to Seyser, what is the car on your other photo? Do you or anyone else here have any idea?

Good Question.  Bumper is not easily recognizable.  At first I thought it was about a 50's Pontiac but not enough chrome for a Pontiac.
 

seyser wrote:

 

 

Nice photo and letter, thats an early Diesel Seventy-Five.

 

Hi, Folks.
I've been fossicking around in my files doing some re-arranging and found some that might fit here. The first one:



Just my 0.02.

 
1938
A Caterpillar Diesel Tractor in underground mine.