Is it the tranny or the ham

The problem - at 1 mph while slowing down for a stop or red light I get this, well what seems to be a hard shift right before stopping. When I take my foot off the break to go I also get this hard shift. At first I thought it was my breaks sticking. But, I was told a few things. It could be a tranny problem with a bad selonid or something to that effect or the ham which is what I was told is something in the rear suspension. The car is a 2000 v-6. There are only 2 two types of trannies buit for this model. Any suggestions. Don't want to get robbed at the mechanics.

Thanks.