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My LS7 swap is going well and I'm having the clutch done while everything is apart. I asked the shop to look at the couplers. They said they look almost brand new (GM parts). The tech did say that while looking at everything it seems as though the center of the driveshaft flexed at one point and rubbed against the Torque tube. I recommended poly couplers. I've read a few posts about poly couplers falling apart due to heat. I'll have about 630 fwhp from this swap but I really don't drag race. Can I get by with the factory rubbers?? Here are some pics (Posted in General as well by mistake )
You already have 12mm couplers so it should be fine. The 12mm couplers are also used in all the C6 cars so they were factory behind the LS7 and GM expected them to stand up.
The ring in the middle of the drive shaft is to limit how much the shaft from acts like a skipping rope when you over-rev it. Changing couplers will not prevent that from happening again. The only way to change that is with a larger diameter driveshaft.
I went with driveshaft shop couplers in my TT with new bearings, but if factory couplers were to be used I would go with the zr1 couplers their slightly more thicker then the rest of the oem 12mm couplers
LOL! YEP,,,,, That problem is caused by OVER REVVING the engine. BUT,,, I know that your thinking " WHAT" How can I over rev the engine when it ELECTRONICALLY controlled at 6250 RPS or what ever it set at.
AHHHHHH<< ANSWER! If you run 3rd Gear up to red line and speed shift to 4th gear "and in the adrenalin rush haste to shift gears " GRAB 2nd GEAR BY MISTAKE,,, you have just mechanically over revved the engine to somewhere north of 8000 RPM (depending on how fast you catch the mistake and if the clutch did a full engagement.)
When I pulled my 02 ZO6 drivetrain apart I had the same issue. So after some research and asking a LOT of smart people, I was told that it is caused by OVER REVVING the engine.
I purchased the car BRAND NEW OFF THE LOT with 12 miles on the OD.
I "have never over revved the engine.. SO, I asked my SON and my WIFE if they may have had a little SHIFTING ACCIDENT.
Poly or stock couplers
)
WHAT" 
How can I over rev the engine when it ELECTRONICALLY controlled at 6250 RPS or what ever it set at.
. If you are staying with stock shaft (which is fine) I would get the DSS couplers or OEM ZR1. 
