4 speed question

[cypressbog]

Are all 67-72 4 speed trannys (sm465) the same between C-10 to C-30?

[Gunuserc15]

I'm no auto professional but I did do some research on the Muncie. I believe in the larger trucks the gearing was lower in the tranny.

[cypressbog]

Hmmm, still a direct bolt-in? That would be nice. My current 4 speed has a granny low which is useless, and with the 530 rear gears, 50 MPH is about max.

[69GMCLonghorn]

It wasn't meant to be a usable gear all the time, just to get you rolling with 150 tons behind or in your truck. I like it for crawling along in this great city of LA to avoid slipping the clutch. Between the various transmissions, you won't have a different top gear. They were all 1:1. They didn't know the meaning of OVERDRIVE back then. You'd have to ditch the 530 gears for something more highway friendly. The only difference from one tranny to the next in that generation are the other gears. There was an SM420 which had an even LOWER granny gear. Then some of the newer but still pre-O/D ones has a higher and more usable granny gear.

[SS Tim]

Just remember the CH/SM465 was not the only 4-speed between 67-72 there were also the New Process 435 and 435CR different ratios and different applications. Plus of course there was the C10 only 3-speed with an O/D that was similar to the base colum shift 3-speed.

[Bigdav160]

Is there an A833 that would bolt in? I know some versions of the A833 had a OD ratio in fourth.

[SS Tim]

There was the RPO MM7, its the NP250 IIRC that is the chevy version of the A883. Not sure how much of a bolt-in it is but the big problem is even finding one.

Now what exactly is this truck with 5.30 gears. Don't recall anything lower than a 5.13, except the 6.17 H0110 that was in the 14K GVW C30 dually chassis cab.

[cypressbog]

Sorry, 513 rear gears. I bought a 68 1 ton with 9 foot stepbed in 2012.

[cypressbog]

I added a pic of the trans that I'm looking at buying. Looks like a Sm465, but it was installed in a 67 C-10, that's why I'm asking here. I didn't know the 465 was installed in half-ton trucks, always assumed 3/4 and 1 ton. My trans is on it's last leg and really need a good replacement.

[SS Tim]

Can't help with the trans ID at this point but I can recommend trying to find a 4.10 drop out from another truck. That alone would be a permanent 20% overdrive. If you were to find, and you are going to have to look, a NP-435CR would really help the drivability especially if you are empty a lot.