Re: Trailblazer SS T-case?
Here's a media blurb from GM. TBSS uses a 4L70E, which is sa derivative of the 700R4. I wouls expect it to use the same 27 spline output shaft that all 700R4's / 4L60E / 65E use.
http://media.gm.com/us/chevrolet/en/product_services/r_trucks/r_c_trailblazer/index.html
The vette tailshaft housing (or whatever you'd call it) with a custom adapter would be the way I'd approach it too (I've thought about the very same type of project). I thought I saw Keisler or one of the other T56 vendors offering a shifter on the main case (the inspection plate ahead of the tailshaft housing) but when I went to look at it last, I couldn't find any info.
I don't think the adapter would be all that hard, if you can address the shifter in another location. If that's the case, it gets to be a set of flanges with a spacer (tubing or pipe or something) in between to set tcase in the correct location. Would be best (with whatever you do) to make it such that you can do the welding, then flatten the flanges (skim cuts with a mill) and then locate the bolt patterns / holes in the flanges, so that you don't have to worry about alignment during welding (because it WILL move, especially with the amount of heat required to get a good solid weld).
These guys ask the same question. The SilvySS tcase is definitely a NV149. The answer posted for the TBSS, I don't see any reference to anywhere else.
http://www.silveradoss.com/forums/index.php?showtopic=40216&pid=466235&st=0&#entry466235
Take a peek at Car-Part.com. There were 7 listings for 2006 TBSS tcases, ranging from $625 to $950 (and a $Call). I'm sure one of those yards would be willing to verify the spline count / configuration for you (especially if you sounded like you might buy one).
Another resource would be Rockland Standard Gear. RSGear's George Kreppein (he's in charge of reman's) is very knowledgeable, and probably can help you with both of your issues (front shifter, and tcase info). RSGear builds the Tranzilla T56, which is rated for 1200hp / 1000 ft lbs. However, I must add that that uses the Viper 30 spline output shaft, which isn't likely to do much good if you need a GM 27 or 32 spline setup. Their C5 units are rated for 850 ft lbs (due to the smaller output shaft).
I have to say that George was very helpful in building the tcase for my truck. I've got a NV146 (which doesn't really exist). Basically, its a NV246 with no low range. Its a NV136 with 32 spline input, and the 4L80E mounting face, but is controlled just like the NV136 that came out of my Bravada.
Good luck, and keep us posted.
'JustDreamin'
