2nd gone again
 

Well second is slipping again already after only having it back for about 3 weeks. They told me they changed the band. Any ideas on what could be causing 2nd to keep slipping

First. Who would they be.
If you have been taking it to the same dealer/shop, are having the same problems.
My .02 I would venture to say you are a guinea pig.
If it was my truck, I would find a reputable repair/tranny shop that has someone willing to perf/ the T/D and show me what they have found. Give me an estimate to repair it and issue a warranty statement/coverage with the finished job and be paid after the road test. If you can`t find a shop to do that, you`ll need to search further until someone will. Other wise they are screwing you over. Also be advised, you get what you pay for...My .02
The other solution is buy a trans from one of the trans shops know by business with other members. Hope you have better luck in the future:cool: