Clutch Chatter Or Bad Tranny ??, S54 Tranny Options

[Remy]

Hey all have a quick question while on the drive way with the ebrake down and in 1st gear if I let go of the clutch slowly without giving it gas the tranny terribly shakes and slowly crawls forward is that clutch chatter or do I just have a bad tranny, bearing, pressure plate, misc... all together ?? And yes I'm aware that if you don't give it gas and let off the clutch it'll stall and cause vibration/shutter on you but this is a different kind of feel in case someone wants to be a smartass lol.

-More info on the tranny-
-Clutch was supposedly change a year ago before I bought it so about 4 years old I drive like a grandma so I don't beat on it either.
-It's written 96 with special auto marker so its a used tranny thats been swapped so not the original tranny.
-Unknown Miles on the swapped s54 tranny.
-Leaked tranny fluid like crazy the first year I bought it didn't know about it because didn't drive it much my bro drove it and he didn't tell me about it although now I've fixed the problem. He didn't care because it wasn't "his" car....and he's a honda guy so he didn't really approve of the car and when I bought the car it was runnin rough, misfiring, shorted and burned wire harness and leaking oil and later on found out about the tranny fluid leak.
-I'm sure some things been damaged because of that I always wandered why it was so hard to shift when I first purchased the car, I though it was because of the short shifter.
-Ran penzoil syncromesh for 2 years, now runnin royal purple syncromax 75w90 alot smoother shifting now took 1 month to break in the tranny fluid haha...what I mean is that didn't notice any difference till 1 month later after the switch.
-I believe this is whats causing my vibration on acceleration problem too u really notice it if your going uphill.
-Full tune-up have been done on this car the start of summer.
-The good news is that I didn't give up on the car yet.

Could use some advice or second opinion on what it is Thanks all.