What do I have to change over on the motor?

 

Wht about going from 2.8 to a 3.1 can u use the wireing and all??

 

Fir your first question, just get a flywheel for whatever year the automatic 2.8 is from. For your second question, just use the 2.8 wiring on the 3.1.
For the questions you didn't even know to ask, this isn't a swap, it's a replacement. You'll get more help in the V6 sub-forum. And if you have to replace a ruined 2.8, forget 2.8s and 3.1s, what you need is a 3.4 from a '93-'95 F-car. Direct bolt in. Still uses the 2.8 wiring, computer, et cetera, you just need the 3.4 injectors.

 

Well I have a 5 speed..so if I went with the 3.4 will it bolt totally up and I can use the computer and everything.from.the 2.8 or do I get the 3.4 comp??

 

This doesn't get any simpler. You just need the 3.4 long block assembly, the 3.4 injectors, and a 3.1 flywheel. Everything else comes from your ruined 2.8-water pump, front cover, accessories, pullies, mounts, manifolds, wiring, distributor, everything.
The 3.4 injectors let the 2.8 computer run the 3.4 injectors.
The V6 subforum has several of us who have done this, me included, and even a couple of step-by-step guides.
The cost was about $200 for the 3.4, another $100 in gaskets, and a few Saturdays of work. Not a big deal.
The reward is 25% more torque! You can easily feel that. More torque always feels better! Highway MPG may go down 1-2, but in town MPG won't suffer.

 

what's the reason for the 3.1 flywheel? if it's to get a neutrally balanced flywheel, the later 2.8's had them too

 

But what if the OP has too early of a 2.8? The one he just lost may not be original, it may be from an '85. Ya never know.