I suddenly feel the need to defend my transmission choice.
Heres my
As I have researched it.
The A-580 ( nag-1 ) trans against a 6.1L SRT-8 is not the same trans as a 5.7 or v-6 even though they have a "auto-stick"
One of the biggest reasons for going with it is it hasn't been done before. The other biggy is it's a blast to drive especially when tweaked. I hang out with the local SRT-8 club and work on SRT-8s The easy choice would be a 5-speed stick. That kinda goes against the whole point of building something unique.
The A-580 is a close ratio 5speed ( only one overdrive. ) much nicer then a 3 or even 4 speed auto.
There are three issues that I know about. A updated shift strategy. ( Not an issue with a aftermarket computer ) A fluid leak at the electrical connector and a bad seal on the dip stick tube that lets water get into the trans. both of which can destroy the trans. ( and can be fixed for a couple of bucks. )
As far as durability. Hennessey runs 600hp out of the 6.1 with a stock trans. The only trans failure was from over heating the torque converter. So now there is a updated converter and a 650 hp option. ( no trans probs so far. ) GS Motor sports kit runs 500 rear wheel hp and 507 ft LBS of torque at the rear wheels. The only trans option... a better TQ. Heat is a killer of any trans. heat is caused by the amount of tq to weight. The Cuda is almost 1000lbs lighter then an LX car so that should help.
PCS, the maker of custom trans controllers, builds a computer for this trans used by the military. Russel has helped me a lot with the complexities of trying to make this trans work. His words were " It's fairly bullet proof." When I asked about whether I should just use the 545RFE ( HEMI truck trans ) His said "Well they are a lot less forgiving we've broke a few.
My biggest fear is not being able to get the trans shift tables right for a compromise of a smooth shift at light throttle and a firm shift at wide open. I do like a challenge. Time will tell. Some times if feels like it may be obsolete before I finish it!
Sorry if that sounded like a rant just my