How much power can they take?

 

The 7½" rear is used all the way up to 2002 in the LS1 cars. They'll take quite a bit, as long as you avoid slicks and big clutch dumps or speed shifting. Shock loads are what kills them.

The 200 can be made to stand up to alot. It's what came in the Buick turbo V6 cars. The guys that build those know how to keep it alive with 500 HP or more.

 

Thank you. While I have your attention, What kind of gearing can I put in that rear? I have a 2.73 in there now (I just jacked the rear and turned the wheels, counted the revolutions of the drive shaft) and I came up with slightly less than 3 revs. I'd like to put in 3.42 or 3.73 posi gears as this wouldn't be my daily driver and would make an occasional trip to the drags. Would cheater slicks be OK while using the TH200?
Please bear with me if I pester you for more info but you cursed yourself by being an apparent source of valuable info.

 

Go here for a list of the available gear choices http://www.drivetrainspecialists.com...=28&cat=GM+7.5

To get the right posi, you need to know how many splines your axles have; 88-back came with 26-spline axles, 90-up mostly came with 28-spline. 89 could have either, but more likely the 26.

As far as what would be "OK" for the rear, alot depends on driver technique, and probably a good helping of luck too. Some people can make them last for years, others explode them on their first pass. It's a calculated risk... do what you can to stiffen it up, like welding the tubes, use a girdle cover, solid pinion sleeve, etc.; but there's no guarantees either way.