I was thinking the same thing, Spencer. From what I've read I think the "Ford" pattern is actually the standard Borg/Warner T5 pattern and GM made them build a case that would fit there "Muncie" pattern. The "Ford" pattern is more plentiful. Knowing what will exchange is a great help. It's likely we will have to fab something. Here's a pic I found:
I was looking at trying to find a decent World Class T5 from a Camaro and a back half from a Mustang and build it. Used WC T5's go for around $500 locally and about $350 on ebay. BTW be absolutely certain they are WC t5s before you bid. They have to come out of an '88 or later Camaro/Firebird. I guess WC gearboxes have a couple housing mods that make them more adaptable to an upgraded gear set. I've still got to find out more about that. So I'm up around $700 before I even start rebuilding... We'll get into that later...
OK so the estimated torque handling difference between the WC and nonWC? 265 for nonWC and 300 for WC. I'm not sure how they come by this number. I'm sure they are worst case. I've heard of tons of guys racing these (WC T5) with no trouble for quite sometime. There isn't that much difference. If I was just swapping a street motor in I'd just spend a couple hundred bucks and get the nonWC. Get an S10 version They go for like $75! Get the "Ford" tailhousing and you've got a nice 5-speed for the street for a few hondo.
OK it's not a direct swap. You've got to find a place to mount the torque arm. I don't know what the overall length is but I'm betting it's different than the Sag4. Then theres the tailshaft: Need to adapt the driveshaft to the output shaft of the Ford T5.
SO back to G-Force. I was planning on finding two T5s and splicing them together with a rebuild and one of G-Forces Straight-cut Dog Ring gear kits: $1500. This moves the torque rating up more towards 450.. There are a few gear options there:
3.22 2.94 2.46
2.05 1.94 1.54
1.34 1.34 1.22
1.00 1.00 1.00
.59* .59* .59*
.73* .73* .73*
.90 .90 .90
The one's with stars are syncronized 5th gears. I don't think 5th gear is that critical to me and that .59 looks like a pretty awesome highway gear. At $1500, not cheap. You do get a pretty stout 5-speed that only weighs 75 lbs. For $2500 you can get a brand new T5 from them in the configuration we've been talking about (GM main case, Ford tailhousing) with the Straight-cut Dog Ring set installed ready to bolt on.
There are a couple other options out there for guys who have more bell housing options than me. The later Camaros had Tremecs and TKOs. They both tougher, and a big difference in weight. About twice as heavy at 150 lbs. I think. If I've done my research right.
I've got time until I need to buy anything so I'm looking around a bit. I'll post new info when I get it.