The above assessment was not my experience. I daily-drove a '64 Cat RHM for 25,000 miles. TV linkage adjustment was easy per the manual, and it drove fine. The shifts were normal, it was that RPM drop going into 2nd. The car did sit a number of years before I bought it, it did have to get new seals & a filter, but afterward- no issues. Have the same trans in my GP (console-shift). That car I never drove much before mothballing it, but it went very well. It's going back in (with new seals / filter - low mileage car). If it sh*ts the bed, I'll upgrade. Cadillac never used the RHM tho- Olds & Pontiac only. RE "63 Olds Delta 98" - you obviously meant the 88. Not up on Olds' specs, but I believe the senior Olds' wouldn't have had the RHM either, only the 'junior full-size'ers.
Apparently the RHM was used in all but the Bonneville and Star Chief, which used the older 4 speed design. Olds used the RHM exclusively, and Cadillac not at all. It seems the RHM was foisted on the smaller wheelbase Pontiacs because Olds sales couldn't justify it's production alone. I guess ensuring that the transmissions are running "Type A" fluid solves most of the shifting complaints. Modern Dextron fluids are not recommended. That would explain why a lot of them died in the 70s here in Canada, they discontinued "Type A" and replaced it with "Dextron 2".
Yes, according to GM parts books, and that's what they want you to use, but apparently Dextron is quite a bit different, a lot thinner but with better heat characteristics, but not as viscous. When I had my Twin Turbine I was told by an old GM transmission mechanic who knew the differences that the Twin Turbine will run on Dextron II, but not happily, - the shifts will be harsher. Apparently Type A was quite a bit more like Type F, just not as thick. Rock Auto used to sell it, don't know if they still do. Just like when they recommend Type A in the power steering, it's best to use Type F instead of power steering fluid or Dextron II which will cause it to squeal. Here again, we changed the power steering fluid in a buddy's old T-Bird to Type F because the Dextron II was far too light. My 66 Electra liked Type F over Dextron II in the power steering as well, it squealed and stuttered with it. On the cap it says "Use Type A". Of course I wouldn't use anything but Dextron in a TH350 or 400. My Mercedes has Dextron II in it, and it's a manual, and the service manual specifies it right off the hop. So there are applications that it is suitable for and not only is it recommended by the manufacturer but by car specialists too. So yes, GM does claim it is backwards compatible. They also claim ethanol gas is OK for older engines, and that modern high detergent synthetic oils are fine too. But is it good for it? I guess that's for the owners to decide. In my experience, no, it wasn't. My RHM didn't like Dextron II either, so the trans shop that I took it to used a type of hydraulic oil that had close to the same properties as the Type A, and it was a lot happier and smoother as a result. Just my experience.
