Question for the guys running 3.73's with a 6cyl and manual trans

[72step]

Originally Posted by 1976gmc20

Yeah, mine did too. Of course the speed limit was 55 back then.


You pickup isn't a short bed stepside that came out of Colorado by any chance, is it ???

Hey bud, my truck is a short step but is a one family New Mexico truck that was more on the green side than blue originally and wasn't two tone. I kinda chose the color combo at the last minute last summer before I sprayed it.

[1976gmc20]

Originally Posted by 72step

Hey bud, my truck is a short step but is a one family New Mexico truck that was more on the green side than blue originally and wasn't two tone. I kinda chose the color combo at the last minute last summer before I sprayed it.

Mine was solid, that medium green that sorta looks like a forest service truck did back then.

I got stupid when I went back to college in mid-life, and decided I didn't need two vehicles living in town and I sold it to some kid. Later I saw it in the college parking lot and he had apparently tipped it over on it's right side

I originally traded firewood for it. It came with a bumper sticker in the rear window that said:
"Eat More Lamb - 50,000 Coyotes Can't Be Wrong"

[72step]

Originally Posted by 1976gmc20

Mine was solid, that medium green that sorta looks like a forest service truck did back then.

I got stupid when I went back to college in mid-life, and decided I didn't need two vehicles living in town and I sold it to some kid. Later I saw it in the college parking lot and he had apparently tipped it over on it's right side

I originally traded firewood for it. It came with a bumper sticker in the rear window that said:
"Eat More Lamb - 50,000 Coyotes Can't Be Wrong"

Interesting! Mine was bought new in Espanola, NM by a great uncle of mine. It was light metallic green. Was going to go original color then paint guy showed me 60s colors and ended up with nassau blue which I love. Now that I have her running good ;man I love the 230 6 with 4spd and 3.73. She runs real good and pretty economical compared to my 72 hyped up sbc 327.

[frankslagoon]

how about putten a Saginaw 4 speed in. that would give ya an extra gear on those hills. but ya can't use the columm shift. I've got a couple 3 sp. overdrives and they ain't hard to find . but my 283 just barely has the power to really work one even with 3:73. GM never used any rear ends higher than 3;73 with the 3 sp. O/D in any vehicle

[TwoFiftyShifter]

I think 3.42 is a heck of a good ratio for these trucks with OEM transmissions. 3.73 is wound a bit tight for non-OD, even with a six-banger. With 3.42s you could cruise at 70 and be turning about 2750rpm.

[72step]

Originally Posted by TwoFiftyShifter

I think 3.42 is a heck of a good ratio for these trucks with OEM transmissions. 3.73 is wound a bit tight for non-OD, even with a six-banger. With 3.42s you could cruise at 70 and be turning about 2750rpm.

I wonder if these would fit our trucks? Not a bad price.

http://m.summitracing.com/parts/rmg-4900701

[72step]

So I guess it calls for a series 3 carrier which does not cover up to 3.73 so you would need a new carrier. You could modify a 90s or newer chevy 6 lug rear end which are commoly found. in 3.42 then there goes originality so meh.

[1976gmc20]

Originally Posted by 72step

Interesting! Mine was bought new in Espanola, NM by a great uncle of mine. It was light metallic green. Was going to go original color then paint guy showed me 60s colors and ended up with nassau blue which I love. Now that I have her running good ;man I love the 230 6 with 4spd and 3.73. She runs real good and pretty economical compared to my 72 hyped up sbc 327.

Honestly I don't know what ratio mine had, but probably whatever was standard (3.73?) for 230/420.

I used it to haul chain saws and gas, etc when I was working in the timber, so I didn't have to use the big truck or the "nice" K-10 with the camper. Then we moved to town, and I used the short step side to commute to work.

I don't remember the gas mileage (~15 ???) but yeah - it was a heck of a lot better than the 1971 K-10 with 350/350 that was lucky to ever get more than ten Actually, the big GMC with the V-6 got as good or better mileage loaded down with logs (20-25K gross) than the K-10 automatic pickup

[curvedglass]

Originally Posted by curvedglass

Thanks for the info. Baby steps - I will start at .045

Just gassed up at lunch 18.01 this tank - and regular is $2.19 here.

I went to .046 (hey swap meet feeler gauges)

I just filled up - 2nd tank in a row to break 19mpg. $2.11

I think I finally have a handle on the tune. Truck is usable in all three gears now and I can maintain more speed on hills. I can live with it until either the trans blows or the motor does - then I make changes

Trans blows - 3.73 and 700r4

engine blows - 350 / 700R4 3.08 rear stays put.

[1976gmc20]

Originally Posted by curvedglass

I went to .046 (hey swap meet feeler gauges)

I just filled up - 2nd tank in a row to break 19mpg. $2.11

I think I finally have a handle on the tune. Truck is usable in all three gears now and I can maintain more speed on hills. I can live with it until either the trans blows or the motor does - then I make changes

Trans blows - 3.73 and 700r4

engine blows - 350 / 700R4 3.08 rear stays put.

If it were me, I would swap the 3 speed for an SM420 4 speed manual with deep reduction low gear, and keep your good mileage rear axle ratio.

That way you will never find a hill that you can't get started on

I had a 1965 C-10 with the 230 and 4 speed and used to take it up jeep trails in Colorado

[sharkskinman]

Ooo Ooo I want a OD for my 3 spd
Might want to upgrade to Saginaw syncro