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3.73s and 35s with sm465

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80blackgmc

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Hey guys,

I am just wondering if anyone has ever run 35" or 37" with 3.73s and sm465? If so, what did it act like in traffic/highway? Was it a dog?
This truck is really my daily driver and I want to get some decent highway cruise ability, but I would like it to be able to get out of its own way in traffic too. I know that the granny low on the sm465 is there, but it is a low gear and not sure if it would be usable. I don't really use it with the 4.56s unless when I hauled heavy heavy stuff. I have a diesel for hauling now.

Currenty the truck has broken front 4.56s and healthy rear 4.56s. I have a set of 3.73s for it that I can use, but want to make sure I'm making the right move before I put them in.


Thanks guys,

Igor.
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Post up said 3.73's and someone will buy them . Get 4.56 for front . No sense downgrading when the rear is set up already ( and mostt important to have right ) .

Hell I would try to install the 4.56 upfront myself .
 
I ran 35's, 3.73's with an SM465 for a few years. It was fine around town and decent on the highway. With the really low first it was also fine for crawlin and general wheelin. The SM 465 tolerates taller gears a lot more than an auto does IMO. Second gear is 3.58:1 versus 2.48:1 (TH400) or 3.06:1 (700R-4) and you don't have a front pump and TC eating up power.

Cruise rpm on the highway is decent too...

The largest i ran with that combo was 36" TSL's, and that was fine too. Hell, i even regularly towed our 21 foot camper trailer (5000+ lbs loaded) with that combo and a lot of that was in the mountains.

4.56's, 35's, and 65 mph = 2850 rpm
3.73's, 35's, and 65 mph = 2325 rpm

Rene
 
Yes, I'm just not sure what to do. If I get axles and a locker for the front, and spend the time to put new gears in and bearings, might as well go 4.56 again. That way it'll work better with 37s and I'll actually be able to tow something with it if need be.
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on my k10 I ran 3.08s and 33s for so long, I got tired of the high gears and now I have 4.10s and I don't want bigger tires because I like the low gears.
 
11 years ago I used to pump concrete out of my old 74 that had 33's 465 and 3.73's. Worked out great.
 
I have 35"s 465 with 4.10 gearing and I think its a perfect combo. But If I had to choose between 3.73 and 4.56 I'd go 4.56
 
3.73's and 36's were fine for me. Not so wound out on the long freeway trips to the wheeling spots. If I stayed on the highways at 55, 4.10's would have been fine for me, but the freeway requires 70 mph, which was wound out enough with 3.73's, I would've hated 4.56's. My one tons came with 4.10's, which I'm gonna keep. With switching to 39.5's at the same time, I think it will be similar to what it used to be.
 
i have 3.73s, TH400, 5.7L motor, and 35s and I hate the acceleration, or the lack completely of acceleration
 
I just installed a sm465 and already had 3:73s with 35s. so far I love it but if put in your situation Id go with the 4:56s.
 
Yes, I can see where an auto, a small block and no gears can feel "sluggish".

My '05 Diesel has 3.73s, 37s and auto. Its got way more "jam" then the 355 in the '80 (diesel is chipped with trans mods), but it still has lag outta the hole. It probably makes 3x the torque of my 355.

But you know, crusing at 1300 RPM at highway speeds is not so bad. Not on a 355 tho, 2k-2300 would be ideal.
 
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