I have a 87 f250 4x4 6.9 idi regular cab long bed. The body is rusting off it . I found a 87 f 250 ext cab long bed with a 5.8 2wd . I know I will have to change the dash and engine wiring and cut a hole for the 4x4 shifter but I was wondering if the ext cab would fit on my frame with a short bed instead of a long bed.

 

Not quite, and for two reasons:
1. The "hump" in the frame is in a different spot.
2. The ECSB is slightly longer than SCLB

 

That's a bummer, I was kind of wondering the same thing only with a ext cab long bed to a quad cab short bed on a 93 f250