If you open the link I posted above near the top right hand corner it has HPI Racing and under it is the manufactures number 86336 this is the HPI number. I like the way Tower Hobbies all ways list the OEM number in their listings. All so you can go to any of HPI web sites and down load any of their manuals that have a break down with part numbers. Do not mind helping just letting you know in case you need other information in the future. Yes it will not hurt to see how the gearing you have goes first and if need be you can change latter.