I'm sure there is. But this is not that.

Any other guesses? I'm not sure where to start diagnosing this. Checking the transmission fluid level occurred to me, but that seems super involved based on what I read here (unless I read it wrong).

So you've checked the u-joints?

2-3 shifts off the gas are normally rough. Omly from 2-3 tho. Never had any other issues

Mine is from just about every gear. It's not the shift point though. I'll be in the gear, let off the throttle and coast a bit, then punch the gas pedal. That's when this clunk/thunk/jolt thing happens.

This should be the first thing you do.

Thanks for providing a starting place. I took the car to my mechanic and went on a drive with him. He says it's not a transmission problem, but rather the differential. I asked about replacing the differential bushings. He said that might help, but also that it might not make all of the problem go away. @FIGS I mentioned your bushings, as I have seen others online use them occasionally. Can you chime in here with your thoughts? If I can mitigate this thunk feeling/noise with new bushings fairly inexpensively, I'd like to try that.

Odds are pretty good if the bushings are bad, the diff itself has been pretty badly abused. Replacing the bushings just about requires removing the diff because you have to do all four at the same time.

So you are suggesting spending another $2K on a Giken LSD while I'm in there?

Actually, I'd pop off the cover and take a look inside to measure the backlash and see if the gears are still good. Then I'd do the Giken!

I would go through the usual inspection but it can be difficult as the driveshaft carrier bearing is under a heat shield. Get the rear end in the air and move the wheels back and forth to check for diff engagement lash and force required to spin the wheels. There are a lot of places it can develop slop. the driveshaft, the guibo joint ahead of the pinion or internally. it could even be a rear axle. Just take is one piece at a time and you will find the issue. Our bushings will certainly help reduce the amount of driveline deflection, but you want to make sure all bearings and joints do not have an issue first.

Mike

Did you ever find out the problem? I'm having a similar issue. I'm thinking it may be the guibo.

have not seen the Guibo make a clunk since its pretty heavily damped, but it's pretty easy to inspect.