Had another modeler ask me to put a reverse cam gear in a 56 so while in the process I decided to see if there was any real difference between the SAI182TD34 which is suppose to be the p/n for the 62 and the SAI130T34 which is the one for the 56. I had previously ordered and received two for the 62 and one for the 56 plus I received another to install with the 56.
I removed both of mine (62&56) from the packages to make a comparison and if they are different I sure can't see or measure it. The lower photo is the 56 and 62 gears right out of the package, 62 is on right, the stock gear removed from the engine is at the top.
Then dug out the stock gear I removed from a 62 just to see if there was any difference between the stock 62 and 56. Was a little surprised at what I found. If you look at the top photo you will see the 62 gear is slightly wider than the one I removed from the 56. (ya the 56 is a well experienced engine).
I really doubt any of this means a whole lot as I don't feel the difference in gear width will make one iota of difference in performance or longevity and the overall length measurement at the bearing is identical. What I don't know is if the first reverse gear I ordered and installed in the 62 is like the one I received on my second order of if somewhere along the line Saito changed the part. Not worth tearing the 62 down to find out but if anyone still has a 62/72 gear from the original stock (SAI182TD34) before they went on BO maybe they could measure the thickness of the gear? According to my digital calipers the stock 62 gear is 0.143 and the stock 56 gear is 0.118