In my opinion, I wouldn't see why they couldn't be interchanged. As long as they're both the one piece design, and are of the same WMS to WMS. But then again, that's an uneducated guess.
Well, I don't own the truck no more, but when I did run the VIN last, it showed as a standard '86 with the D35(which it has). So it may be possible special order; the build sheet would show for sure, but I never looked for it.
Sorry for the hijack Jim.
hmmmmmmmmmm interesting sorrey about :hijack: ill stop now