Like the title says, what's stopping me from using a T5 from a pickup for my T5 conversion? I notice that nobody does it.. so I'm guessing there is a reason why.
I'm not going to say this is the way it is because I'm not sure but, the tailshaft may be a different length. It is also possible the shifter comes up in a different spot and you may need to change the shift rail and the rear tail section of the case. Again, I don't know for sure but that may be a difference. If you have access to one, take some measurments. I've seen your handy work, you are a good mechanic =)
Actually it is a Mazda M5R2 or a M5R1 (depending on F150 or Ranger). The rest holds true. The Shifter is too far forward to use, and is a bit longer to the tail as stated. The ratios are for truck pulling instead of car driving.