As far as a turbo 350 tranny goes, are they basically all considered equal while in stock form, or are some better then others based on what they came in?  Would one that came in a 3/4 ton truck be built any different than one that came in a car?  Just curious.  

They are all about the same just some are lock up trans and some are non lockup trans the lock up trans has a electrical plug in on the driver side.  

Yep, they're all pretty much the same aside form the lock-up/non lock-up models. The only difference from the factory would've been what torque converter was installed from the factory.

In today's world, you can build a TH350 to be as strong/stronger than a TH400 with aftermarket internals. The beauty of this is the TH350 is a lighter trans than the TH400, so you get physical weight savings, and the internals are lighter so there's less parasitic loss to turn the transmission.  

Th350s came in alot of duty applications from 6cyl to v8s. The truck versions are stronger but they have a longer tail shaft than a passenger car (9" vs 6")so you'll have to shorten your driveshaft.