Hi

The NA transmission is a 722.618 (W5A330) rated at 330Nm, the SRT6 transmission is a 722.633 (W5A580) rated at 580Nm.

The 722.633 transmission is used by Mercedes on M113 V8s and its M112 supercharged V6. The NA and SRT6 transmission have different gear ratios and can't be easily interchanged. The SRT6 transmission has a larger diameter driveshaft connection, to use it in an NA you need to change the connector on the transmission, or fit the front half of the driveshaft from an SRT6 (or an SLK32). The Transmission Control Units (TCUs) are also programmed differently. The TCU is programmed with the gear ratios and the diff ratio. If you fit a V8 transmission to your NA, you'll need to fit an SRT6 TCU and a SRT6 differential (3.07 ratio), you'll also have to recode your Engine Control Unit with the new diff ratio (ie. change it from 3.27 to 3.07). If you don't change the diff, then you'll have to get your existing TCU reprogrammed by a specialist (eg. Eurocharged) as this can't be done using the Mercedes Star Diagnostics software.

My advice is that if you've got a problem with your existing transmission in an NA Crossfire, then get it repaired or replace it with a Mercedes 722.618 transmission. To swap to a transmission from a Mercedes 5L V8 is a lot of work. If you have an SRT6, then no problem.