This sprinkler will be a good 1/2" taller than the old style.
The nozzle is adjustable. No need for 1-2-3 anymore.
If the sprinkler you have now is just leaking or not spraying properly you can just change the insert and nozzle.
www.sprinklerwarehouse.com/v/vspfiles/search/search.asp?Extensive_Search2=N&keywords=toro+340