thx twip i knew about this post but lost it and old posts come in handy instead of creating new ones. gm dealer is a rip off but ill try and find what torsion bars i have. i might go with the 30 mm thickness ti add strenth.

well gm no longer sells torsion bars at all

Gitch, your best bet for heavier bars is a low mileage ZR2 at a wrecker or pick-n-pull. The ZR2 Blazers mostly came with the 30.69mm bars, and I think some of the ZR2 pickups came with the 32.51mm bars, but after a ton of research I'm almost certain that there is no way to confirm the bar size without either measuring or checking the part number. Even a VIN search doesn't tell you which t-bars you have, although it does tell you which t-bar keys you have.

As is stated earlier in the thread the last 3 digits of the part number are stamped into the head of the bar. I have heard that if you're really lucky and have a lepruchan in your pocket when you check, there may even be a sticker on the bar that has the part number too, although I've only heard of 1 person who had this lucky occurance.