If you are using a t5 to put in a model A or 32 ford you should take one from a S10 as the shifter is closer to the engine. A t5 from a mustang will be a couple inches behind so you will have some problems shifting. A lot of people use the s10 transmission case with camaro gears because of better ratios.
The GM and Ford T5s have different mounting patterns to the bellhousing. You might be able to mate the Mustang gearbox with the S-10 tailshaft and shifter housing. I know it works between the Camaro and S-10 units.