Th350 transmission problems

[TRWalker20]

About a month ago I lost all forward gears in my 86 square body. Decided to pull and replace the trans with a rebuilt one from a guy. Swap went fine and I've driven it for a month but this morning I get a lot of shuddering on initial acceleration. Drive for about a block and have to stop at a stop sign. On this acceleration I get more shuddering and real sluggish acceleration this time. I drop it to 1st to get across the highway. I get up to speed and it works pretty good. Get to a red light and can barely get off the line even when dropping to 1st. Pull over to check things out and lose all forward gears. No clue what could be the issue seems unlikely that the trans would go out in a month. Thanks for any help.