saginaw transmission identification

[Pops]

Can anyone tell me what my 3 speed syncro transmission came out of:
Main Body: GM 28, casting 3925647, date J221
Tail:3873886, GM 45
Pad: S2S05
Thanks.....

[Pops]

quickly found under a Camaro site. it looks like I have a 1971 Camaro 3 speed, Saginaw synchronized transmission behind my 1966, 250 inline engine. Every casting # was correct to a 1970-72 camaro. I see where there is a small square hole cut in the floor to fit the shifting components. (PO)
So here's my next question: I googled for quite some time and it appears that a Saginaw, such as mine, was used in Chevy trucks in 1966. The prior year's transmissions were muncie sm318. Is this correct? Do I have the right transmission even though it's out of a car?
I further read that this car transmission would bolt right in; however, you needed to use bolt and nuts on bottom of trans since they were not threaded on truck. (poss have this backward)

[BarryGMC]

Actually the Saginaw is a better trans. I think it was also used as a HD version 3 speed in trucks. Barry

[bigblockv6]

Originally Posted by Pops

quickly found under a Camaro site. it looks like I have a 1971 Camaro 3 speed, Saginaw synchronized transmission behind my 1966, 250 inline engine. Every casting # was correct to a 1970-72 camaro. I see where there is a small square hole cut in the floor to fit the shifting components. (PO)
So here's my next question: I googled for quite some time and it appears that a Saginaw, such as mine, was used in Chevy trucks in 1966. The prior year's transmissions were muncie sm318. Is this correct? Do I have the right transmission even though it's out of a car?
I further read that this car transmission would bolt right in; however, you needed to use bolt and nuts on bottom of trans since they were not threaded on truck. (poss have this backward)

The 1966 GMC sales brochure does list the SM-318 as the standard 3 speed trans in 1/2 and 3/4 ton trucks in both 2wd and 4wd models.

[Pops]

there is a lot of Chevy information about the Saginaw transmission in 66. Since the 250 inline used in the GMC is a Chevy engine in 1966, I wonder if that would explain the Saginaw possibility. Perhaps the 318 was behind the gmc v6?
Thanks for input.

[bigblockv6]

I mentioned in a previous post yesterday that the SM-318 was the standard gearbox in 1966 on "all" 1/2 to 3/4 ton trucks including 2wd & 4wd models and the same goes for the 305E and 351E V6 engines.

[Pops]

Fair enough big block. I find it tough to get exact info on 66 gmc. I thought they all came with back up lights in 66 too. Saw a base 66 from orig owner under 50k miles and it did not have backup lights. I get diff opinions on seat belts too (though they prob all came equipped with factory holes. It appears Canadian chev trucks have some variations from US. Not sure about gmc. Thanks for feedback.
Its too bad most of gmc's history is buried somewhere under old torn down plant in Pontiac MI. great we have this forum to share and compare.

[BarryGMC]

I have seen enough Saginaw trannies behind Chevy 6 engines from 65-72 to believe they are factory. If not people swapped them out a long time ago. 66 Chevy trucks offered a sm 318 a sm 326 and a bw t89. I have never seen a Warner trans but I have seen lots of Saginaws. Barry.

[BarryGMC]

Thought on the 66 with no 66 stuff. Back up lights. Spin on filter. Seat belts. Grill letters. Look at the 6066 GMC guy stuff. My green 65 is titled as a 66. But I call it a 65. I have had 2 this way. Its common on the 66 titled trucks. My truck was built in April of 65. But first title shows 66. I consider it a 65. And represent it as such. Barry

[Pops]

Hey Barry. Haven't swapped info in a while. Hope all is well.
Just wondering about your last response to this post. Did your 65 gmc that was titled as a 66 come with an inline six or a 305 v6? I would assume the v6.
As you know, inlines didn't enter 66 gmc's until 66 models. But then again????