1. My 1984 240 has two hoses going from the radiator to the expansion tank. The lower one comes out the bottom of the expansion tank, where it's 3/4", and feeds into the radiator end tank about halfway up, where it's 5/8." The factory hose is a molded hose, $12-13 and not commonly carried around here even in foreign specialty auto parts stores. HOWEVER: my local parts store carries a coupling that takes 5/8" hose at one end and 3/4" at the other. With this, and a foot each of heater hose in the two sizes, I was able to make the hose and install the radiator on a day with decent weather instead of two days later, when the hose would have been delivered but when it rained 4" in one day. Cost me under $4, too. If your local parts store does not have these couplings, you can make one, at slightly more expense (though still under $12) by going to your local hardware store and buying brass tubing-to-pipe-thread fittings (I'd recommend 1/2" pipe thread) and a brass coupling, and assembling your own. This, actually, is what I'd do if I'd thought of it, since the coupling I got is plastic. When you install the assembly, use the natural curvature of the heater hose from its life in the box it comes in to fit it. The final assembly looks kind of cool in a British car way - shiny hose clamps everywhere.

2. The new radiator was about 1/4" lower than the old one (new one is all metal, old one has plastic end tanks -- maybe this is why?), and rattled around in the rubber fittings that hold it in place. Some chunks of inner tube solved the problem. If you don't have an old inner tube around, go to where trucks or farm equipment get serviced, and you can probably pick one up for free. A great thing to have when maintaining a car or house. One will last you for years.