Forget who it was on this sight told my brother his stock explored swap with the same 456 gears and 31" tires almost wants to spin the tires when accelerating to merging into traffic.
That was me. And that's exactly what mine does.
Stock Explorer engine, with stock Explorer cam and exhaust manifolds and most smog intact.
Stock 4R70W and converter with no modifications.
The 31" tires are mud-terrain as well, which likely has something to do with it, if yours are more street friendly. As does the Detroit locker.
And as said, it's hard to accelerate to merge, because it wants to spin both tires and slide sideways. Fun under the right circumstances, a bit annoying in traffic, or on a quiet night int he neighborhood and all you hear is the chirping of tires instead of crickets.
I don't often accelerate heavily in reverse, so can't compare from your perspective on that unfortunately. But what they said about your torque curve could be part of it. A 300hp 302 is no slouch, but my 240hp has gobs of torque literally right off idle. That with the stock converter could be the only difference needed to make that variation in our experience.
What kind of exhaust setup do you have? Big duals by any chance?
Mine's a single 2.5" with Magnaflow muffler and catalytic converter.
Runs strong until 4,000 rpm and then starts to fade, then runs out of steam at 5,000 rpm. Where it sounds like yours would just keep pulling hard until you let off the pedal.
Paul