Tractech isnt a new outfit. Ive never heard anything negative about them.
No set up is exactly drop in on differentials. Once you disassemble your rear end, you will have to have it put back together with the specs. Rear ends arent a bolt in job like a carb or headers. They require special tools like dial indicators etc to set them up. Gear lash is a very critical part of a rear end staying together and for wear and tear.
In order to install that setup, it will require removing your ring and pinion gears. Since the lash has to be set on the gears, then it will require the previously mentioned equipment. Drop in refers to not having to have any special tools to install it, IE, carbs, intakes, headers, and most transmissions. Those jobs can be done with simple hand tools, reassembling a rear end takes dial indicators, shims, etc etc etc.
Remove diff cover, remove center pin bolt, slide out center pin, push axles in and remove c-clips, remove axle shafts, turn diff till the spider gears come out, and pull out the side gears. Installation is reverse of removal.
Obviously this is for a c-clip axle but isn't much different then any other type of diff.
If we are talking about a 4-spider diff (like in a 14-bolt FF.) you would have to remove the carrier but because you will be reusing your carrier you can just put it back in where it was....but why would anyone in there right mind have a 14FF (or any other heavy duty truck axle) in a hotrod nono:
The 4-spider might be a bit more difficult but still requires no gear setup.
I have replaced spider gears on both 2 and 4 spider gear diffs using only tools that EVERY shade tree mechanic (only "special" tool I used on the 4-spider was a torque wrench) would have.
I call that drop in and this is NO DIFFERENT then something like an EZ-locker which has been installed by many people in their driveways.
Now that we have gotten that out of the way back to the question...
I just got to finally look at the setup on that link you sent. That is something totally new. I figured it was just another conventional posi type differential setup like Eaton or Moroso sells. Ive never seen an outfit like that, but the company has a good reputation, as I have seen their other stuff in operation, so I wouldnt be scared of it.
The powertrax no-slip is fine for a daily driver, it only has some mild quirkiness that is easily controlled by the drivers right foot. I've been using one in my daily driver for the last 18 months +/- and it has worked perfectly.
Installing the powertrax is fairly simple - but I was warned to be sure to use new (or like new) side gears and a hardened cross pin (which came with the diff.) to avoid trouble later.
I didn't do the installation because I was having a 9" narrowed and the carrier changed from 28 to 31 spline axles so I had the machine shop install the diff. since it was all apart anyways.
I'd be interested to learn more about that other (PTD) diff. If I find anything I'll post back here. My first thought was that it is a variant on the torsen differentials.
If you remove the carrier just remember where the shims went (left and right) and be sure to torque it to exact specifications, a new differential is harder then it sounds i've been there and done that and broke it before I realized that it was my fault it shattered.