OK, I consider myself fairly knowledgeable about my Formula, and cars in general except for 2 things

#1 Installing stereos and #2 Transmissions

That being said, I have read conflicting things on what I need to do when I swap in my new rear axle.

I currently have the factory original axle with the Highway Friendly 2:77 gears and Peg Leg axle rear.

I built a New/Spare rear with all new Gaskets/Bearing/Races/Seals/Lug Studs etc..... and a Eaton Posi w/3:73's

and I would like to get it in this spring, but need to know what to do with the trans. If All I need to do is swap out a sensor I can do that myself, but if I need to have the gear on the trans changed, I am going to have to take it in, because the last time I tried to take my x-member off I broke 1 bolt & decided to stop, and figure a shop can do it, and break the rest and drill em out and fix em LOL.

Any way to easily know? The other issue is before I bought the car, the engine had been swapped to an 89 350, so I am only assuming it to be the Original trans, but there is no Speedo cable, so I am guessing it has the VSS.

And are the parts still available form GM? or will I have to look aftermarket? Any recommendations?

Thanks.

 

This is your 90 Formy right? Electronic speedo with a vss? If all you're needing is the correct driven vss gear to correct the speedo after the rear end swap, that's easy. The correct gear is available from GM. If this is what your asking, then all you need to do is remove the vss from the trans tail housing. Raise and support the car. Remove the one 10mm bolt holding the sensor in place, remove. Shine a light inside the tail shaft to see what the color of the drive gear is inside the tail housing. Make a note of the color. That's important to know, to match with the replacement driven gear. Same is true if your speedo is cable driven.

Once you know the color of the trans tail drive gear, search the forum for gear swap speedo correction. You should then be able to find the correct GM part number to match your combination. If not, post back.

Good luck