Jr. has less power and less features compared to Sr. I found a used Sr. for my truck for $500 which is still a chunk of change, but it was worth it. If your looking to buy a used Smarty you'll be looking for version S-06. Also if it doesn't have the Revo options, you an go on Madds site and upgrade it for free. Also the version S-06 can be sent into Madds and they will upgrade it for you to the POD version for 100 bucks I think.

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