I was looking on HPI's website at these two engines but dont know what the difference is between them. one is $96 and the other is $105. What gives? Hahahaha
http://www.hpiracing.com/products/en/15105/
http://www.hpiracing.com/products/en/15107/

I have a RS4 3 18ss and NEED a new motor. People are saying OS is where it's at but when my Nitro Start T-15 was running, I thought it was bad as$. What do you think? Is it worth spending the couple extra bucks and getting the .18 or for $67 on Ebay, sticking with the stock .15? Thanks, Joe

get the OS. I just went through the same discussions you did. I went with the OS. I posted step by step install also

Yeah but I also asked people to post a link to where I can get some cheap and I've got nothing back. I dont know 100% what I'm looking for or if I need new parts. I wanted to know if I can use the stock clutch bell and shoes off my current Nitro Star. If you can get me the link to your step-by-step install that would be great.

you can use all nitro star 15 parts on the OS. You will need the HPI 20mm motor mount and a racing clutch and mounting hardware

Thanks for the reply. I'm going to look into it.