89 L98 F-bodies have the 9-bolt rear end, remember? If you have a single catalytic converter you have a 2.77 ratio rear end. The cost of a new posi unit and gears would be well into the $600 range, so try to find yourself another 9-bolt with 3.27 or 3.45 gears. Easier would be to find a 10 bolt from a 90+ thirdgen or fourthgen with disc brakes and swap that in. Dont forget with a gear swap you will need to change the speedo gears in the tranmission so your speedo reads right, and possibly the governor in the transmission as well so it shifts right.

Sounds to me that for $200 you should go with the AFPR, and port the plenum and runners while you have them off to install it.

 

The "stall" and "converter" are the same things. It's actually a stall converter or a torque converter.

 

Oh

But what in the hell is all this AFPR talk about?

 

Just pull a posi unit out of a matching rear end and install it yourself. Make sure you put some good gear oil in there, and you can RTV the diff cover back on.

Go back in there a little down the line and do your bearings and etc if you want peace of mind, but for now, that would seem best. You could get out with just the posi unit to add to your rear for under 50 bucks I bet, another 15 bucks on some gear oil and voila.

Then port and gasket match the plenum and runners along with that Adjustable Fuel Pressure Regulator. You could do all this for under 200 bucks if you weren't lazy and hit three or four junkyards for that perfect posi.

I got a posi unit that looked brand new for 35 bucks last year, and someone had already ripped out the spider gears to make it easy for me to pull. A guy I know through a friend offered 100 bucks for it so I let it go.

 

Im not trying to be rude but I know it will sound like I am. Thats not true. I have an 89 formula with a 10 bolt rear end straight from the factory.

 

Wait a minute.. I just now got what Kevin91Z said..
No dude, our cars have 10-bolts for the most part I'll be damned if you find a 9-bolt seeing as how rare they are

 

theres a few 9 bolts that pop up every once in a while, but why would you really want one? yea they are tough rearends, but the gearing/parts for them are hard as hell to find....it would just make things more difficult and more expensive..i'd take a built 10 bolt like mine anyday..


I still say get new gears....its gonna cost you more than 200 bucks, but there isn't much you can get these days for cars for under 200 bucks...

correct me if i'm wrong, but I think he's referring to an Adjustable Fuel Pressure Regulator..

 

My buddy's is an 89 iroc L98 350 700r4 stock......no 9 bolt under there....

 

just counted, used all my fingers and thumbs...However, I do have a friend with an 88 Formula L98 and his is a 9 bolt. They are geared a little differently too, its like 3.27 to the 10 bolts 3.23. So its not like you can feel a difference or anything...Other than that, i dont know much about our rear ends...

 

I have a single cat GTA 9 bolt with 3.27 gears.... its done me good so far.

 

Somewhere I heard that a LT1 cam will swap right in and cause a slight increase in power? Yay or Nay? Ebay had one with lifters for $23 + $10ish shipping the other day.

 

Nope, 10-bolts usually. SOMETIMES you will encounter a 9-bolt in Formula's and sh*t.. but for the most part our cars are 10-bolters

Oh, ok. I never knew what that meant

 

theres something about having to move the dowl pin like .030 (i think) but other than that it slides on in. You should see some increase I would think, lift on them is like .475 or so

 

Yes, an LT1 cam is GREAT on our 3rd gens. However, I would personally get a custom cam

 

i was wrong, you have to push the dowel pin in .30"