Yes, it makes sense, and I knew they were offset. I didn't center mine since I needed the full width axle. I hope you're aware that if you shorten the long side your rear axle will then be about 5" narrower than the stock Camaro axle. So at that point you'll need to not only tub the rear, but narrow the frame rails back there also.
You could purchase a long side axle from another rear, and have the short side tube lengthened to the 28.5" length, and it will center the pinion and get it to the same width as a stock Camaro rear axle.
Really depends on what your plan is for the whole build. Pro street-then narrow it; more stock look-then widen it.

 

If I could get away with not having to narrow it, then that would be great. I'll have to do some fitting and see how everything matches up.

 

Do some more research. Guys who tub their car and narrow the rearend tend to want to have the pumpkin centered as viewed from the back. Sometimes it's out of necessity to clear the suspension, sometimes it's for aesthetics. Centering the punkin puts the pinion off center to the transmission, and this is done all the time without having any driveshaft issues. Pinion angle and driveshaft angle are three different things.

 

I really don't care, personally, if it is dead center. As long as everything works. I don't want to have to tub out the wheel wells, or mess with the frame either. It should be easier to find a Ford 8.8 housing so that I can scavenge the longer side if I need to. My biggest problem with finding what I have, was wanting the positrac. I'll take the one I have out of the bed of the truck and see how it measures up on the car.

 

You do have to make some changes to use a rear axle with offset pinion, so that the axle to driveline angle matches up to the transmission to driveline angle. The offset will give your rear axle a certain amount of angle to one side, so you can't adjust your pinion angle up or down to cancel out the driveline to trans angle. When I use an offset pinion rear axle, I figure out the driveline angle to the pinion, and then the down angle in front. If the offset in the back is the same as the down angle up front, then I point the pinion directly at the trans output shaft so it doesn't vibrate or create vibrations from having two angles in the rear, to the one in front. I did this on my Falcon, and also the Nova I'm helping my buddy build. I have no vibration at all.
One thing you also need to consider to help decide if the differential needs to be centered, is the driveline tunnel. If your car will sit low, then you may have to center the pinion or cut and rework the tunnel to keep the driveline from hitting.

 

I think I may have a solution, but I'm not sure how much it will run. I had the idea of calling a machine shop, and seeing if they can make me an extension to the existing shorter end. Then, have someone weld it on the existing smaller one. The other option is to maybe have them machine a new housing tube to match the longer end. That depends on what they would charge to do it. If worse comes to worse, the local UPull has a number of Fords in their yard. I can look there and see if they have one that will work. I have a lead on a welder, I just need to get in touch with the guy and see if her can do it.

 

It's pretty easy to extend the short side 3" and use a stock long side axle on that side. Simply get a piece of tube the 3.25" diameter and correct thickness wall. Then have the short side tube cut, and get someone to weld in the 3" long section. There's no problem splicing the axle tube if it's done right and the ends are kept square to the tube. I've had axles narrowed and they often cut a section out near one end or the other and butt weld the tubes together.
Anyone with a lathe large enough to accept the 3.25" tube can face it off straight to prep it for welding.

 

I called a local machine shop, and once I was over the surprise of them answering this late on a Sunday, I got a quote of 225$. That is all welded up to a complete tube. Which isn't too bad. I'd probably be looking at about that just to get a hold of another axle housing around here. Then I'd end up paying more to have the scrap one cut and welded on mine.

 

Sounds like a decent price. A long side axle from the wrecking yard should be around $30, so you should be set once the tube is done. Might need to grab a long side brake hose, or extension to get the caliper hooked up after lengthening the tube.