Just rebuilt 3 months ago, pump is whining and is hard to pull forward but pulls normal in reverse. Replaced pump, and convertor. Guess my question is which one needs to be replaced again?

 

I would be taking it back to whoever rebuilt it and telling them to fix what they screwed up. You should not be having problems with a properly rebuilt transmission within 3 months of having it rebuilt. Something is seriously wrong.

When the trans was rebuilt, was the trans cooler replaced? Were the lines flushed with solvent? Was the trans cooler & lines pressure & flow tested to be sure there was no problem within the cooler? What brand converter?

Unfortunately no one will be able to tell you exactly what is wrong with it without opening it up. I would recommend you find another builder and have them go through it to figure out why it has failed again. If you don't find the cause of the failure, and you just replace the parts that have failed, you will be repeating this process over & over again.. Good luck with your project.