ok heres the problem i put 3.73's in the rear of my 88 iroc i know i need a 15 drive and a 45 driven i got the gm parts useing the pt# sethirdgens gave me the problem with that is that the 45 driven gear only works for electronic speedos and i have a mecanical driven speedo that gear had a 1/4 inch of play on my mechanical gear shaft for the speedo...... gm tells me they dont make that 45 tooth for the mechanical driven speedo soo they said they have an all plastic one for a 77 most likely a 350 trans can anyone help me get the proper gear i need to have a workin speedo???

 

8642620 is a 15 tooth drive gear
25522497 is a 45 tooth driven gear & comes with the sleeve.

 

it will fit the 700r4 with no problem??? and is that a gm pt#???

 

Yes & yes. These are for a 1987 Camaro 700R4 with a mechanical speedo. Been through this many times & I work for a GM dealer.

 

thanks very much man i just ordered it and it will be in tomorrow i really appreciate the help

 

i have 323s stock in 83ta with a 700r4, my ? is i am going to 373s will those part numbers work for me

 

i am not changing the gear on the input shaft only the gear that the speedo cable screws to. thanks

 

The factory setup for 3.23 gears is 17 drive & 44 driven, pn's 8640517 & 25522495 respectively. 38 tooth driven with a 15 tooth drive is not ideal for wear.

 

86 Iroc z - now has t5 with 3.23 ratio rear. Got a t56 tranny, which probably won't go in till 07. Will put in 3.73 rear in at same time. Can I use cable driven speedo - if so which drive/driven gears to use?

 

ok ricktpi i really appreicate the info but i was still wondering, u said from the factory, for 323s i have 17 and 44. i want to know with putting 373 in what driven gear do i need. u r a HUGE help. thanks

 

I'm glad I'm not the only one in the dark about the speedo gears. I have a 1989 Formula, T5 w/ 3.73 rear gear and 25" diam tires ("16s"). Rick, can you point me in the right direction too?

If not I understand you're not here for a free consultation. Thank anywho...
Eric