codyvette

iTrader: (24)

Yes, you need one not connected to the tail housing. A short arm is more effective but does resonate more noise into the cabin.

Utinator

I won't be running nearly as much HP as you, but I got the BMR torque arm and trans cross member. It allows the torque arm to connect to the cross member. Mine is non-adjustable, but BMR makes an adjustable version. My set-up is a 4L80e and stock 10-bolt (for now).

HCI2000SS

iTrader: (2)

You can run either the long style TA (which fits like the stock one) or run a the tunnel style one which is shorter. Both styles can be mounted to a relocation crossmember which is obviously best. Unless you want pure all out straight line grip, and don't care about handeling or braking as much, and don't mine more interior noise, then you'll probably want the long style arm. That's what I'm doing myself

MidwestChassis2

iTrader: (1)

There is always some variances on which torque arm you want but the general rule of thumb is if you are into handling you will want a long torque arm and into drag racing you want a short torque arm.

Again there is variances that will make you want a long torque arm for drag racing but generally for handling there is no reason for a short arm and handling specific vehicles. A short arm can induce the rear inner tire to come up during hard corner braking. You would choose a long arm in drag racing for manual vehicles to tame the hit down some especially for N2o combinations.