Is it possible to replace a vacuum modulator on a C6 without having to drain the tranny?

Also, is there any particular modulator I should install in the C6 behind a 300cid?

 

if i remember the part store listed 2 diff. modulators for my 79 bronco's C6. which the parts house will list which you need it there is 2 diff. ones used on yours. you don't have to drain the tranny to replace it. it's mounted high on the passenger side of the tranny. just be sure you don't lose the little pin that fits inside the modulator when you pull it. you'll be good to go.