I have stock gearing and I want to upgrade my performance. what gear(*) do I need to change and where do I find the procedure? Kris

What is your stock FDR?

If it'* a 3.06, you can just swap out the diff and sun gear for a 3.33 combo.
(This being possible because the 3.06 has a 35/35 or 1:1 gear set)
Programming will be needed of course.

I dont know my RPO codes. My trunk lid plackard is worn off. Reprogaming covered courtesy Sinister Performance. Money in hand, what am I looking for? Kris

This my 94 SE. I dont know what the stock gearing is. Its an L27. So when I do this I need to replace the diff and the sun gear?

Then crawl under the car and tell us what the trans assy code is. The ID tag is located on the outer end of the axle housing. Should be able to see it right up behind the pan.

You're looking for one of these.

4PFW
or
4YMW

Duplicate post deleted. Please don't reply to yourself, but instead edit your last reply.

The Diff and sun gear are not different between the 2.84 and 3.06. The difference is INSIDE the trans. The drive and driven gear on the final drive are different ratios. If you're 2.84, go to a 3.06. If you're 3.06, go to 3.33.

For example, the diff in my cars is the sam diff used for the 3.33 gears. But it'* bigger than the 2.84/3.06 diff.

The plackard isn't on the trunk LID. It'* on the spare tire cover. Go to the dealer if you can't find it and give them your VIN. They'll tell you.

This is incorrect. Go look at an ATSG manual..

To get a 2.84 FDR it takes a 35/35 gear set multiplied by a 2.84 diff.
To get a 3.06 FDR it takes a 35/35 gear set multiplied by a 3.06 diff.
To get a 2.97 FDR it takes a 37/33 gear set multiplied by a 3.33 diff.
The list of combos goes on..

SO

As long as you have a 35/35 gear set (which a 2.84 would) you can bump up to a 3.06 or a 3.33. You just need the diff and sun gear from a trans with the gear ratio you want.

If you want to get real specific.. You really only have to change the sun gear and the spider gears in the diff. But there’* no real point to that unless the side gears are messed up.

My goof. I was recently given information from that very ATSG manual and either interpreted it wrong, or was given the wrong info.

Nevertheless, I'm beginning to wonder what the goal with this car is? I think that needs to be answered before we go further.

I already tried getting my RPO codes from the dealer....93 was too old...so I'm guessing 94 isn't gonna work.

getting that code off the trans is probably the only way to know.

Will, I am doing my best to learn how to performance modify. I intend to drag race it this Summer. why this car? I owe on it and until I can sell it for more than I owe on it I ll keep working on it. I Love my bonneville and dont even to sell it. the way it handles at high speed is very encouraging and sound. The motor has only 30 k on it so a rebuild is a while up the road. The L27 is limited but it is what I have to work with. Ill check with dealer about the codes and look at the trans for it too. From what I gather here It sounds like I need to swap out the diff And sun gear, depending on the actual trans arr. where do I find the procedure? Kris