That's a nice old Cat HT4 loader that someone has fitted with a dozer blade.
The HT4 was Cat's first hydraulic traxcavator and it was simply a long track D4 with loader tower and bucket added to it.
The 4 cyl engine in the Cat 619 that kshansen speaks of, was the D340T.
Not exactly a roaring success of a engine, as with most of Cat's early DOHC engines.
You'd be struggling to find one complete and running today. Even Cat referred to them as a "low tolerance engine" - i.e. one that needed constant attention to maintenance as their tolerances were low and it didn't take much to put them "off-song".
On the other hand, the newer 3400 series engines when released, were called "high tolerance engines", they could cope better with tolerance that were out of spec.
Richard Campbell of NZ Contractor magazine has a "write up" on the rare 619 Cat scraper. The first 619's still had a cable operated bowl!
Operator comforts were few and far between with these machines. Seats were like park benches, A/C was the wind in your face, and they bucked and bounced like the best rodeo bull!
Caterpillar’s model 619 motor scraper was the very first of their ‘600’ series machines and introduced quite a few innovations
contractormag.co.nz