Non-Alfa truck question

["Howard and Pat Warren" <warrenwood@domain.elided>]

Okay, don't kill me, but I trust this group of auto experts more than
anybody else <g>.

My father owns a 1985 Ford F150 truck, inline 6 cylinder (don't know the
displacement but it's carb'd) w/ automatic transmission, P/S, P/B.  This
truck has well over 150k miles on it.  He uses it like a truck is meant:
hauling lumber, and driving to deer camp <g>.

A few days ago I took him truck shopping for a new one.  He was surprised at
the sticker prices.

So my question is this: how hard is it to swap the engine and transmission
with something newer, and save him some money in the process?  Are later
model Ford engines pretty much "bolt-compatible"?

Thanks!

Howard K. Warren, Little Rock, Arkansas
1991 164L, "Peregrine", 71k miles (hers)
1991 164L, "GrayHawk", 79k miles (his)
1984 GTV-6, "Falconi", 134k miles (toy)

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