I wouldn't sham on transmission fluid. Crossfire transmissions (really the whole vehicle) are like women, very sensitive and picky. The type and quality of fluid you use can greatly affect how your car rides. If you want to go for the best kind of transmission fluid I would go with the Fuchs Titan ATF 4134 - Mercedes MB 236.14. It is the new transmission fluid that is now used universally in all Mercedes transmissions from 97 - present. It can be used for MB236.12 transmissions. Below is a link that talks about it. They even mention that it is compatible with Chrysler Crossfire specifically on the second paragraph from the bottom.

Fuchs Titan ATF 4134 for Mercedes - meets MB 236.14

I went and spoke with the Mercedes dealer about it and its compatibility with SLK's and Crossfires and the guy didn't recognize it by the name Titan 4134 since that's its manufactured name before they change the bottle for Mercedes. They recognize it as MB134 or ATF134 or something like that.

It's expensive via internet since it is imported via Europe but I'm getting another transmission installed into my crossfire and have to fill it completely (torque converter and everything, about 8-9.5 quarts) later this week and my fathers mechanic knows where to get 5 liter jugs for $36.00. I don't know if they have a website but I'll find out their info for people interested. Its in the Florida area. I'm sure there are other places that can get it for a better price as well.

Other transmission suggestions (performance transmission fluids):
TCI Max shift fluid
Red line
Royal Purple
Even though I don't race my Crossfire I definitely would choose performance fluids for the best tranny fluid.