I have a rebuilt 700r4 in my Camaro that has Synthetic fluid in it, just as the rebuilders recomend. It seems to be leaking from All of the seals ! I have heard with synthetic oils, you should break in a new engine with conventional oil, so all the seals and gaskets will seal up. Is it the same with transmission fluid ?

Tom I put Amsoil ATF Syn in my 700r right as it was done being built up for me and Ive not had any issues with leaking seals but I also have only put on about 500 miles on it too. Im pretty sure that no break in is required since there is no 'seating' of rings to cylinder wall type thing going on inside the tranny.

Same here , I used royal purple syc for my TPI 700r as recommended. No issues. Last resort I would try a can of TransX or Cargo to expand seal but if its a new transmission, why?

no dont use the tranny in a can in new trannny. take it back to who rebuilt it for you. as for the synthetic fluid few people that i know use it all the time amsoil. they swear by it. none of the trannys that i rebuilt for them never had a problem leaking.