There was a discussion on the ACME board on these recently, link is below, you may have to register to view the forum, which is the Caterpillar Technical Q&A. My interpretation is this, after the long production of the 2U series, the next series, 13A, 14A, 15A, was finally released and I'm sure the prototype(s) of each were heavily tested in the proving grounds, 14A was direct drive, the others were torque converter and or early powershift, don't honestly recall those, more familiar with the older ones 2U's and earlier, and the later 8K's.
Next series would appear to be 35A 36A, 36A being a direct drive transmission with an oil clutch which is the preferred drive train for heavy drawbar work. I can only assume the 35A is a powershift or torque converter, and it was mentioned that 776 of these were built, which may have taken place early in production run, possibly around the time of the 13A-15A's ? I'm not sure, do wonder if the 35A is one with the diesel filled torque converter and how that differs from the powershift trans, but obviously the power shift became the more prevalent design. Seems like a lot was going on when the H's first arrived, first D9's came out as well, same deal being offered direct drive or torque converter.
46A apparently gained engine horsepower and is powershift. I have heard from the the previous generation of operators that the H's were better than the later K's, that seems to always be the discussion, hard to comment having only run K's and not being one who disassembles and repairs them, these are the people that would know a lot more on that and what the facts are.
Cable control vs. hydraulic control for the dozer blade was a matter of preference, lot of people liked the cable control unit operated blade, as it was quick to raise, I forget the line speed of the drum, but they are geared high, same reason that is all they are meant for, not for a towing winch by any means. I'm not sure when they stopped offering CCU operated blades but it was an option for quite some time, before hydraulic was only available, both were available from the 50's to probably early 70's. As far as the orientation of the lift cylinders, early hydraulic models had the hardnose with the trunnion that passed through the engine compartment, like I recall on the D7's and later just the outside of the hard nose, really not sure on that one, somewhere in the progression of things changes took place.
Having rippers is a plus and that r.o.p.s. you hope is a factory engineered and dealer installed or a factory authorized unit, those H's probably did not have them factory installed until late in the series, and for it to be a true r.o.p.s. it should be one designed & engineered, and correctly installed on the tractor to do the job, of not collapsing in the event of the tractor rolling over, which you may already be aware of.
Others may be able to provide better details and correct me here, keep that in mind, also ACMOC and ACME forums should be helpful in addition to this one.