http://www.mylaps.com/en/products/rc4-upgrades/183

Thanks allot....

MRT has a much better deal (cost wise) on an upgrade to the new MRTs that work with RC4 decoders.

I have three of the new ones (which MRT made from the original scan of an AMB I sent to be cloned in 2009) and they work fine on RC4 decoder systems.

Do you have the link for that?

Forgive me for coming late to this conversation but what's the latest word on compatibility? I'm ALSO specifically concerned with OCRC here in California.

today decided to call mylaps office about my older transponder trade in and they told me for the new rc4 hybrid total price 98.96 included with trade in. for the rc4 3 wire which don't work on older system trade is $67.46 and thats not included with shipping, i prefer to sell on ebay or rctech if funtional, than to give it away to mylap. amainhobbies has it for $109 free shipping. what you guys think

You need to think very long and hard at where you will be running and the decoders they use. Ask track owners if/when they plan to "upgrade" < I don't see it as an upgrade at all, thats just me. And according to the numbers you provided they are only giving you $11 trade thats not much. I would keep it for use with older decoders when you go to places that use them, and, just buy a new rc4 for use at places that require it.
edit: don't forget MRT (rc4 compatible) they are $30 less and work just fine.