Which 3OTT Transmission Do I Have
 

I have a leak where my speedometer cable attaches to the transmission. It's my understanding that I need to replace the speedometer (bullet) gear housing and o-rings. I need to know which transmission I have so that I can order the right part. How do I go about determining what I've got?

The truck is a base model 1970 C-10 with a 307 and a 3OTT.

Here are a few pics in case they help with identification.

Re: Which 3OTT Transmission Do I Have
 

I would assume it's a Saginaw but were there multiple model numbers or other manufacturers? Just don't want to buy the part twice.

Re: Which 3OTT Transmission Do I Have
 

Saginaw or Muncie.
Count the bolts on the side cover and note their locations then check this chart. That will tell you which it is.


https://lugnutz65chevystepside.weebl...ission-id.html

Re: Which 3OTT Transmission Do I Have
 

According to the pic at geezer#99's link, since my cover has 7 bolts, I have either a Muncie or a Saginaw. According to some info I found online it's probably a Saginaw due to the bolt tab at the center top.

Here's the info I found online.

"The real trouble with Muncie SM330 is that they are nearly identical to the Saginaw three speeds, the quickest, and most sure way to identify a Saginaw from a Muncie is the side cover;

The Saginaw three speed has a single centered "ear" bolt boss:

The Muncie three speed has two "ears" on either side of the top of the cover:

Re: Which 3OTT Transmission Do I Have
 

I'm also trying to determine if this is likely the original transmission on the truck. Here are the codes I've found on it.

The pics are as follows:

Driver Side Cover
Driver Side Tail
Passenger Side Body
Passenger Side Tail

Re: Which 3OTT Transmission Do I Have
 

These are my best guesses at the numbers

Driver’s Side

Cover –
(first line) GM 8 3952645
(second line) J. (6or8) 9

Tail Shaft –
I 229

Passenger’s Side

Body –
(first line) GM 36
(second line) (3or8)925(6or8)47
(third line) J. 8 9

Tail Shaft –
52 GM (3or8)8(0or6)042

Re: Which 3OTT Transmission Do I Have
 

This is taken from the GM chassis service manual for where the numbers are on the transmission.