starting my t-5 swap

[Smokeshow_1984]

Well ladies and gentlemen, I finally got sick of my horrible fuel milage with my 4.11's, so I bit the bullet and bought a donor car for the swap,a 3rd gen f body with a mild 350, and a t5, which brings me to my question. with a swb truck, anyone have any idea as to the required length of the driveshaft? I know, I know, get it installed first, then messure the distance, But, I dont like vehicles sitting around, waiting. Id like to know before I start ripping things apart.
Subsequently, a 74 250, and 3sp will be sitting around shortly.
Thanks, Ben.