water pump for a 1962 rambler classic with a 196

There are several different water pumps for that era of 196, none are easy to find. You can send yours to a rebuilder. It's affordable, doesn't take long, and might be simplest. There's one in the Detroit area we have highlighted before. You can try to Google it, or someone here will recall the name.

Yeah, I have seen the variety of pumps for these...is there any real difference other than the flange to flange height?  There has been some creative work done on this car before I got it so I'm not even positive this one is "correct"...the pulleys line up, outlets seem to make sense and it pumps water, is there anything else to look out for?  

I'm more curious about the impeller size, depth, etc and bolt locations.  I can verify/change hose orientations easily enough, but if its mechanically different and not flowing right for whatever reason it would be hard to tell.

All the 195.6 pumps for cast iron engines will physically bolt up, OHV or flat-head. The only differences are the shaft length and heater hose outlet location. Easy enough to fix the heater outlet with some hardware store fittings or just swapping the nipples. Also, as TomJ mentioned, some have the plug on top. I believe they are 65 only, but a few may have crept onto late production 64 models, or it could have been a late-year change that won't show up in the TSMs and probably not the parts books. Easy to drill and tap the pump for that even when assembled, just be careful with the drilling!