I just bought a 92 ford f350 that used to have a diesel in it. someone replaced the engine with a gas one and I think it's a 460 BUT the firing order is different than it should be. I have no other definitive marks on it other than this firing order:

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Is it possible it's a 390? I don't know but I need to get a carb and a coil for it so I need your help.

 

It's either a 351m or 400m, these are a "Cleveland" with a 1.1" higher deck.
They share the 429/460 bellhousing so that swap is "fairly" easy.
I don't think you can tell a 351m from a 400m from the outside, the only difference is the crank and pistons.

Just about any Autolite 2100 2 barrel will "work" on there.
If you have to worry about emissions that's a whole new ballgame since neither engine has been made since 1981 for the 400 and 1985 for the 351m I think. They smog out quite clean when set up for their day though even without a cat converter. (The air pump passages are internal, easy to plumb). The edelbrock performer EGR is a super good 4v intake for a heavy truck for that engine, I ran that with a 204-214 cam, 1-3/4 headers, about 330hp, ran good and good mileage.

 

You are right. which model # performer head was it? I think I'm going to have to go get a holley carb or something aftermarket because I don't know where to get my hands on an autolite 2100 + it's a truck which will probably do better with the 4 barrel carb.

 

The INTAKE I used was the Performer 400 EGR #3771 (4v intake)
They also sell a spacer that adapts the Ford EGR valve and also adapts to a 2v carb if you ever need that for smog but it sounds like you don't.
Mine was set up that way here in CA and it passed smog and visual just fine, the manifold is a "stock replacement part" so it's 50-state legal.

I ran the stock iron open chamber heads, just cleaned up the exhaust a bit, and 1-3/4 headers. But, of course you don't need to change that stuff yet it will run pretty good with just a 4v and the Edel intake.

If you find the 400 Weiand intake #8010 it is also good but does not have EGR. I ran this one also on my 5300lb 4x4 so it works good on a heavy truck. Near as my stopwatch could tell me, the Weiand made about 10hp more but about 10ftlb less than the Edelbrock.

Either intake is good if you get a swap meet deal.
With just changing to either intake and either a 600cfm Summit or Edelbrock or Holley or Autolite 4300 carb you will be up about 40hp.