So I am going from 2.73 to 3.42 in the rear axle.

I have the TH700R in my 1989.

I read the gear ratios sticky, consulted the Service Manual, and the TH700R4 Update Handbook.

I am very confused.

1. Does my car have a cable driven speedo or electronic (VSS?) ?
2. If its electronic then I should just be able to use an electronic ratio adapter?
3. If its cable driven, do I need a driven gear, drive gear or both?

From AttilatheFun's post:

I need a 40 driven and a 15 drive?

Re: Sticky: 700R-4 speedometer gears
Okay, I've had enough whining from the lazy and the weak-minded.
So I decided to just start on a cheat sheet. Not all combinations
can be exactly calibrated, but here's the best possible calibration
for each combination given.
This first batch is for anyone using a 700R-4 with any of these tire
sizes on the rear axle of their car:
205/60R15
225/55R16
245/50R16
245/45R17
275/40R17
315/35R17
245/40R18
If your tire size isn't here, don't use these results.
2.73:1 use 41 tooth driven with 19 tooth drive
2.77:1 39 18
2.86:1 38 17
2.93:1 39 17
3.00:1 40 17
3.07:1 41 17
3.07:1 36 15
3.08:1 41 17
3.08:1 36 15
3.23:1 38 15
3.23:1 43 17
3.25:1 38 15
3.27:1 44 17
3.31:1 44 17
3.31:1 39 15
3.42:1 40 15
3.45:1 41 15
3.50:1 41 15
3.54:1 42 15
3.55:1 42 15
3.70:1 44 15
3.73:1 44 15
more no cal.

 

GM did not use 15 / 40 with 3.42 third gens. Nor 19 tooth drive gears in third gens.

Others swear by aftermarket numbers. You will be close with 42, maybe 41, and maybe 43; search a few posts for the GM docs with listings . . .

All 90-92 Camaros were VSS at tailhousing. Cable before.

Speedo gears are available and cheap for the 700; VSS is done at the speedo; skip the enthusiastic ratio adapter electronics.

 

Thanks I ordered the gears from Summit.