I was looking at Gearstar's web site, and was surprised at the specs they give for one of their 2004R transmissions. Looks like it's good (the expensive one) for big HP and big torque. I know folks on here like those, especially to replace a 200 POS etc, but had no idea that they could be built to handle that kind of power.
I haven't ever rebuilt one, and the only one I worked on was in my niece's '87 El Camino. It was the type with dual bolt pattern, which I haden't seen before. I had to pull that one to change the flex plate, and while it was out I replaced the seals, oil, & filter. Seems like an amazing little transmission.

Indeed they are it just takes a few billet (hi dollar) parts to make them tough as all get out---They are very similar internally to the TH700r4. and as far as I know they all have the dual bolt pattern................Dan

I have a Gearstar transmission in my 66 El Camino. It is the 700R4. I only have a 350 cid / 330 hp and it gets all the hp to the rear wheels.