Ed-

Not real sure about the 5.7 but my '84 5.0 had the straight through- I believe they switched shortly thereafter-

I upgraded mine at the time with a "kit" through Nacra & Murray's- It does leave a big hole but I cut my original "straight-through spreader" off and used under the new SS mast fitting for the raked spreaders (completely covers the holes anyway) as a sort of "compression tube" just to be sure and "gooped" the dickens out of it! Worked well for ~16 years until I traded it! IMO it made a difference upwind and was well worth it-



Kirt