I got the trigger and guard. Best upgrade ever. It is pretty spendy though.
The kit
ht tp://kinneysshootingsupply.com/marlin-trigger-guard-trigger-black-15084-p-1350.html?osCsid=8814acae4b77fe7ec536d9a611b3184c
Just the trigger
ht tp://kinneysshootingsupply.com/diversified-products-m-66.html
With the trigger guard you get an overtravel stop and can adjust most of the take up out of it as well.