The plastic throttle arm can usualy be replaced with a single arm servo output arm. ( you can get a different length throttle arm this way too) That covers the .40 FP's air bleed carb... and some others. (works on the .91 FS too [img]i/expressions/face-icon-small-wink.gif[/img] I needed a longer arm on my carb.)

The needle valve.. depends on which one you need. You'll find that some of the Tower brand engine needle assemblies fit some of the O.S engines, direct replacement at much lower cost than the O.S. part.

Tower carries ALL the O.S. parts that are currently available. (some old stuff isn't in production any more...) Call thier 800 number and you can get the parts you need. Your local hobby shop can also get them.. (if you have a local hobby shop) Several other mail order places can get the parts for you too. You won't find much price variance though.