I think the cylinders are all the same length these days. That's certainly the case with my 442 and 638 (38 Specials) and 640-1 (357.) Only the chambers are different.
The cylinder on my 49 no-dash is shorter, but that gun is at least 25 years old. I'm not sure when S&W lengthened the cylinders on their J frame 38s.
BTW, whatever the weight of the 1/4" longer barrel on the 357 models, in my view it's worth it for the equally longer ejector rod that comes with it. On those occasions when I do 10 or 15 round practice drills I think the extraction of 38 Special cases is more reliable with the longer ejector rod.