I have a 3.42 rear gears, my rear tires are 285/40R17 with a 26inch diameter.

My transmission is a t5, it has a VSS electronic speed sensor, it has a white drive gear with 5 teeth

I have no idea where to start on what gear i need to make my speedo work

Since GM T5 speedo drive gears were 7 or 9 tooth, I'd start by pulling the VSS and using a sharpie to mark the drive gear and recounting the teeth.

it is a 5 tooth drive gear i counted correctly.

Its not an original GM transmission it is a remanufactured transmission

i found a website with some kind of calculator and it says i need a 13 or 14 tooth speedometer gear but im not too sure on that and wouldnt know where to buy one

my parts book only goes to 89 but I found in the 88 section you need
Im not sure what year car you have..
This is for a 245/50/16 tire which my be close to your tire??? and get you fairly close..

7tooth drive, Dcode, PT# 14071731 purple
19tooth driven, N code, PT# 14090592, white (sleeve/sensor 25007350)


GM PART # 14071731
PACK QTY: 1
List Price: $8.20
Price: $4.82

GM PART # 14090592
List Price: $25.95
Price: $15.23