You gotta remember, the wheel openings on an Explorer are a tad larger than that of a BII. WORST case scenario, you might have to trim about an inch on the lower rear area of the front fender.If when your doing this you use half inch spacers at the radius arm bushings to move the axle forward a tick, you won't have an issue.
That's it with 33's on 15 X 8" wheels... 3.75" back spacing.
Believe it or not, I had more (however slight) issues running 31's on it when the suspension was factory.
It's all up to you now. Let us know what you're gonna do.
EDIT: I wonder what it is with lifting RED explorers.... LMAO!