GM Speedo driven gear help needed

I need help figuring out and getting the proper driven gear for my coupe.

I've searched around and most of what I've found is info for TH350 and 400 trannies. My issue is that I have a mid-60s Saginaw three-speed that I need a driven gear for. The drive gear, as best I can tell is an 8 tooth gear, (with all the info I've seen in my search, I'm wondering if I counted the teeth right). The rear end is a 2.79 Ford 8" and I have 28" tall cheaters.

I called the folks at Speedometer Service Company and they want to sell me a drive gear AND a driven gear. Seems there is no driven gear to fit my needs. They're suggesting a 10/21 combo. This means I'll be tearing into my ****** to replace the drive gear. This is something that I've never done and don't want to do - ever. They also suggested a two piece cable with a reducer. This only costs $130.

In the search on the HAMB, I found this thread -
http://www.jalopyjournal.com/forum/showthread.php?t=203386&showall=1
Although it's got a ton of info, it seems to spawn more questions then it answers.

Anyone care to take a stab at this and tell me what you can come up with?

If I have to replace the drive gear, is this something that I can do by removing the tail housing and does the ****** need to be removed and on a bench?

Thanks.
Vance

 

On an auto you just remove the tail housing, the gear is held on with a clip. I don't know your trans but if it has a removable tail housing you should be good.

 

It does have a removable tail housing. I guess it's gonna be another learning experience...

Vance

 

Get the equasion for the tires/rear/trans...then set it properly. It's no big deal when you have the right combo.

 

The Saginaw tail housing is easy to remove,look in any good service manual.If you don't want to take the trans apart you can by a ratio adapter to screw on your present speedo drive,about 80 bucks from speedo repair shops.Look online.

 

done this several times on 40 fords with stock speedos--just use the adaptor/ratio box as suggested--works very well

 

Update - I ordered and received a gear set from Speedometer Spe******ts and I'm gonna install them this morning. The set is a 10 tooth driven and a 19 tooth drive gear. This is what the guy there at SS suggested me get. I'll post anything later as I go; hopefully a very happy, positive post and not a new list of swear words.

Vance