You can try to install a v0971 release on RC3 -- but I'm sure that this not works properly 
Why we have make a new release you think?
Small fixes results in a update release like 0.971-3 or so ...
Fel
Thanks. I just figured out an easy way to install older mods on new versions of SMF... using the Advanced feature on the Package installer to set the Package Manager to emulate RC2.
* As I updated from RC2 (not a full install), the Package Manager thinks that all the old mods are still installed... so you have to go to the smf_log_packages table of the database and delete the records of whatever mods you want to reinstall. Then the package manager will allow them to install.
Having done this, the 0971 version of PMX installed smoothly and is running smoothly so far. All the data for the old settings, panels, blocks, etc... is preserved so everything looks and acts just as it had.
I am getting one error that appears near the top of each page : ( Fatal error: Call to undefined function getTemplateLayer()() in... ... /Sources/Load.php(2094) : eval()'d code on line 199 )
I recall seeing this after installing 0971 originally... and fixed it. But I don't remember if that was a PMX or SMF fix.