I was browsing the net, and came across some M90'* for the Thunderbird */C, and was curious if that set-up could be mated to an L67? Having an external intercooler would be sweet IMO. Just an idea. Would there be any benefits?

Sure, it'* possible. It'll involve a lot of LIM modification and some sort of "UIM" to fit inbetween the LIM and the inverted SC. And intercooler tubing.

What about the intake side? It looks like the tb would run into the firewall.

It'* far enough off in every way that it will cost you far more in custom work to get it in there than it would have been to buy an intercooler designed for the proper application to begin with.

Just throwing it out there as an idea. I think it would be a pretty sweet set-up.

The aussies made a plate that allows a RWD L67 to use an external intercooler.
FIT is the company that makes it. A couple pictures of the plate can be seen here and here.
I've seen the price discussed on forums before. I can't remember exactly but it'* a pretty penny.

i want one of those commodores. RWD? SWWWEEEEETTT!!!!!

There'* also the fact that the M90 that went on the Tbird is inferior in every way to the M90 that went on the L67. I mean EVERY way. They're trash.

BTW, the Aussie plate is a huge chunk of cash, even before shipping, and customs.
I don't know why no-one has made an air/air plate for the U.*., but I can't imagine it would be hard to design and machine one out of aluminum.

I know that I am still relatively new to this stuff, but what makes that M90 so inferieor to ours??

The top-exit plate that goes to the intercooler is a huge restriction. Just look at the thing and you'll see that much.
The design itself is several generations older than the Gen3 M90 that the Series2 got. The tolerances are looser. The case is also a thicker, heavier casting, which means it heat soaks that much more thoroughly, and because it'* attached to the lower intake, the intake air charge still absorbs a lot of heat from it. Even without the intercooler, I'm positive you'll still get a denser intake charge with a Gen3 M90. Basically, you're talking about going over to an older, less refined piece of machinery, with major designed-in flaws.