I'm really looking into putting some 3.73's into the bird. I know it has the stock rearend (10 bolt I think..? Not sure exactly.) with 3.23 gears. I need to know the info on splines, etc so I know which 3.73 gears to buy, anyone have this off hand? Thanks!

 

28.

JamesC

 

Thanks James, but for some reason, the only 28 spline 3.73:1's on Summit are for a Ford 7.5" and an AMC diff...

http://store.summitracing.com/egnsea...4294785125+115

Think you'd be able to find the ones I'd be able to buy and have my mechanic do the work. (I'm still scared of having bad gear whine or something, I stay away from the differential, lol.)

 

Look on ebay for gears, while you are at it add a posi unit to the rearend. I would deffinately take it to a rearend shop for the install, everything has to be just right in the rearend, I'd be afraid that I would mess something up.

 

So any 10 bolt 3 series 28 spline 3.73:1 set Will work for me? The rearend is still quite a confusing thing to me, lol. I'd like a posi, but not sure about $$$ right now.

3.73's won't be too steep for the occasional Highway travel, will it? The only reason is that 90% of my commutes are in hilly back roads and I don't really like seeing my RPM's too high. Plus, it'd make putzing aorund town more fun, me thinks.

 

This is just me, personally, but I think you would be better off with something in the 3.54 range. It doesn't kill the mileage and the V6 cars do quite well with those gears.

It's still very easy to get matching speedo drive gears and you can find a fair amount of these in the wrecking yards.

My 90 with a 3.1 did very well with those gears. I will certainly run them again.

 

How much of a seat of the pants jump can you feel with the 3.54's compared to the 3.23's? How much would I be killing the mileage with the 3.73's?

 

If your gonna swap go 3.73's

I'm happy with my stock 3.42's

 

Are you SURE it's 28 I can't seem to find any 28 spline 10 bolt GM ring and pinions.

 

Everything from about 1990 on used the 28 spline setup.

You can probably get what you need from ebay from a 4th gen or an S-10...
----------
I liked them so much that I swapped the same rear into my 87 Formula that had 2. somethings in it and it was great. I noticed an all around better feel with those mid-3 gear sets. Many of those 3.23's were sold because of emissions and not mileage. You will likely see your mileage INCREASE if you switch from 3.23 to 3.42 or 3.5 something.

I know from experience that 3.73 will give you a DECREASE in mileage but an increase in fun!

 

sell the 92 and drive the 86.