OK gang you've helped me before and i trust you can again
i have an 86 f150 4x2 4.9l offi intake holley 450 efi exhaust ..
the stock axel is as follows
S806A 3 08 8.8 6021
the new to me axel is as follows from a 91 f150 xlt lariat
S837B 3L55 8.8 3602
can i take the ring gear and pinion from my old axel and put them in the new to have a 3L08
the 3l55 is to high i dont like my I6 turning 3200 rpm at 70 mph
im ready to put the old open diff back in just to save on fuel and engine wear
thanks for your replys

 

I'm not an expert on the 8.8" by any means, but I don't think there'd be any issues with putting 3.08 gears from an open carrier onto a limited slip carrier that originally had 3.55 gears.

Keep in mind that you do need to do a complete gear setup when you do that though. And if I was going through that much effort I think I'd use new gears.

 

complete gear set up?

 

Yup... it's a fairly non-trivial thing to do where training & experience count for a LOT.

Let me google that for you

 

I've done a few differential setups, although on Dana axles, not on the Ford 8.8 model. Whenever possible with used gears, I like to keep the ring gear mated to its carrier. (This would apply to any model.)

The reason is that any carrier will have a few thousandths of runout side-to-side, and the teeth of the ring gear will eventually wear down differently to match.

If you transfer a used ring gear to another carrier, use a dial indicator on the back of the gear before disassembly to find the high and low spots. Then check the new carrier for runout, and then match up the old gear accordingly.

I've never seen this mentioned anywhere and is something I learned the hard way. It will make your life a LOT easier when adjusting the mesh pattern on the gears. You will be able to get a much more consistent pattern.

As far as new gears, be careful as some aftermarket brands are not that great. You might be better off with good condition used OEM gears versus aftermarket parts of unknown quality and durability.