Is It My Transmission?

[ROUGE180]

What's up Zilvia. I have some questions for you. Your help woule be greatly appreciated. I have an 89' Pignose with all the basics and a swap (S13 finned RT,FMIC,BOV,MBC,C/Os etc etc). I've had it for about 3 months now and I've been noticing new noises and such. When I got the swap done 4th gear used to grind a bit and got progressivly worse. I got some Shock Proof and it worked like a charm. No more noise. I daily drive the car and some of the roads were not really meant for coilovers so I do what I have to do.

As of late, when I shift, I hear sort of a "cunking" sound followed by the car jerking a bit. Nothing to rattle my teeth but it does jerk forward. It doesn't matter what gear I'm going into either. I would like to think my transitions are smooth so I'm pretty sure it's not operator error. Could it be one or all of the following? Low tranny fluid? Worn and overworked gears? Loose transmission mount? I know I can pick up a new tranny for about $200 so it's no sweat. My ultimate goal for the car is about 300-350whp. That being said do you think it's worth up grading the tranny to a Z32? I know that comes with some modification/adapter plate for the bell housing. I was also looking at getting PPG or OS Gieken gears but that may just be overkill. I try to go Touge every weekend and I go to a drift even every couple of months or so. Lets face it. We build our cars to drive and suffer from heavy foot syndrome.

Have any of you experienced this "CUNKING/JERKING" issue before? If so what was it and what did you end up doing to fix the issue? Thank in advance for your help.