Sm465

[tc4x4]

On the topic of transmissions, I have the 4 speed with the granny gear. I beleive its the sm465.

The SM465 is heavy-duty truck transmission is used in light duty and heavy duty trucks. The SM465 was made by General Motors from 1968 to 1991. The SM465 can be found in Chevrolet and GMC full-size trucks, Blazers, Suburbans among other models

The "SM" in the transmission's designation stands for Synchro-Mesh.

Gear Ratios are:

First Gear - 6.55:1
Second Gear - 3.58:1
Third Gear - 1.70:1
Fourth Gear - 1.00:1
Reverse - 6.09:1

I think I have 4.10 gears also, when I'm cruising My rpms are revved pretty high. I'm considering while I have the axle opened up changing to something like 3.73 gears.

Would this make a big difference for cruising?

[76stepsidechevy]

depends on your tire size, 4.10 to 3.73 really isn't much of a drop though. I have 33s with 3.73s and run 2500 rpm at 65.

[tc4x4]

I guess I just got a get a tach to see where I'm at first...

[coreys87]

im running 3:83s with a sm465 and 35inch tires and its about 2300rpm to do 65 mph

[76stepsidechevy]

Originally Posted by coreys87

im running 3:83s with a sm465 and 35inch tires and its about 2300rpm to do 65 mph

Hows it feel on take off? do you have to clutch it a lot? can you actually take off from first gear? I just went with some bigger lift springs and my 33s look tiny now so Im looking at a 35 or 36.

[coreys87]

its really not bad. i only use first gear, no low. do have to clutch it a little more since im used to 4;56's

[76stepsidechevy]

Cool, maybe ill just go with 35s then. It would be nice to get the rpms down to help out my highway mileage a little bit but It probably wont change anyways. New 6" bds springs make the old rancho 4" kit look like it was stock suspension. I only had time to do the rears this weekend and my truck has a wicked rake right now.

[coreys87]

Really? I have been wanting to go to a 6 inch lift from my 4 inch
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[76stepsidechevy]

Yea, I haven't done the front springs yet but the old rear suspension was just blocks on stock springs. Im sure those 36 year old springs were tired. We'll see what happens when I get the front springs in this weekend. Lol right now it looks like a drag car.