I bought a orange box replacement module that has four pins but the one I took off has five pins. What is the difference and will it work on my car?

yes it'll run but if you have not opened its' pkg or installed it yet I would strongly suggest that you grab the receipt (and it) & refund it & buy a $15 parts house black replacement one (a 5 pinner). More info later. What coil? OE? ohm it if you have a VOM

The coil is OE and I went to O'reillys and got their in house module. I will take the orange box back to Summit Racing which is not far from me, Thanks.

Did your box go out or start to miss or are you wanting more perf? If perf I'd start by reworking the advance systems (in order) in the stock dist. A hotter coil & a ballast to match the coil would be the next step. The ECU is pretty much just a switch to control the coil pri circuit though it can only handle (switching on/off) so much current (just like any switch) and the amperage is determined by the coil/ballast combo. New(er) orange boxes have a disproportionate amt of reliability issues (they'll start missing erratically) and have been tested & shown (on occaision) to retard timing at higher rpms which you'd never catch if you weren't looking for that.

I replaced it because the hard shellac stuff that fills the back side of the module was melting into the engine compartment. Every thing was running fine though.

Actually they can bleed like a stuck hog & still function but it does look nasty & gives you thoughts of impending doom such as a breakdown on the way to an important event that you cannot miss. Can raise it up off the fender w 2 spacers and or mount it where there is some air flow. EDIT Nacho posted something on why they melt & at 1st thought it was a high charging rate but after thinking, it way have been something else , a circuit not grounded well inside . He'll post if he sees this